1
|
Wu Q, Quan W, Pan S, Hu J, Zhang Z, Wang J, Zheng F, Zhang Y. Atomically Thin Kagome-Structured Co 9Te 16 Achieved through Self-Intercalation and Its Flat Band Visualization. NANO LETTERS 2024. [PMID: 38869481 DOI: 10.1021/acs.nanolett.4c01526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2024]
Abstract
Kagome materials have recently garnered substantial attention due to the intrinsic flat band feature and the stimulated magnetic and spin-related many-body physics. In contrast to their bulk counterparts, two-dimensional (2D) kagome materials feature more distinct kagome bands, beneficial for exploring novel quantum phenomena. Herein, we report the direct synthesis of an ultrathin kagome-structured Co-telluride (Co9Te16) via a molecular beam epitaxy (MBE) route and clarify its formation mechanism from the Co-intercalation in the 1T-CoTe2 layers. More significantly, we unveil the flat band states in the ultrathin Co9Te16 and identify the real-space localization of the flat band states by in situ scanning tunneling microscopy/spectroscopy (STM/STS) combined with first-principles calculations. A ferrimagnetic order is also predicted in kagome-Co9Te16. This work should provide a novel route for the direct synthesis of ultrathin kagome materials via a metal self-intercalation route, which should shed light on the exploration of the intriguing flat band physics in the related systems.
Collapse
Affiliation(s)
- Qilong Wu
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
| | - Wenzhi Quan
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, People's Republic of China
| | - Shuangyuan Pan
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
| | - Jingyi Hu
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, People's Republic of China
| | - Zehui Zhang
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
| | - Jian Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Hefei National Laboratory, Hefei 230088, China
| | - Feipeng Zheng
- Siyuan Laboratory, Guangzhou Key Laboratory of Vacuum Coating Technologies and New Energy Materials, Department of Physics, Jinan University, Guangzhou 510632, People's Republic of China
| | - Yanfeng Zhang
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, People's Republic of China
| |
Collapse
|
2
|
López-Urías F, Rubio-Ponce A, Muñoz-Sandoval E, Sánchez-Ochoa F. Thermodynamics of resonating-valence-bond states toward the understanding of quantum spin liquid phenomena. Phys Chem Chem Phys 2024. [PMID: 38787750 DOI: 10.1039/d4cp01008f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2024]
Abstract
A quantum spin liquid (QSL) is a state of matter in which spins do not exhibit magnetic order. In contrast to paramagnets, the spins in a QSL interact strongly, similar to conventional ordered magnets; however the thermodynamic stability of QSLs is rarely studied. Here, the thermodynamic properties of centered hexagon nanoclusters were investigated using the Hubbard model, which was solved using exact numerical diagonalization. The total spin, spin-spin correlation functions, local magnetic moments, charge and spin gaps, and magnetocaloric effect were analyzed for a half-filled band as a function of the ratio between the on-site Coulomb repulsion and electronic hopping (U/t). The centered hexagon nanocluster exhibited an antiferromagnetic (AFM) behavior with exotic magnetic ordering. Resonating-valence-bond (RVB) states were observed for intermediate values of U/t, in which short-range spin-spin correlation functions were suppressed to minimize spin frustration. The AFM order was examined in terms of the Néel-like temperature derived from the temperature dependence of the magnetic susceptibility. An interesting result is that the systems under external magnetic fields exhibited an inverse magnetocaloric effect, which was remarkable for intermediate values of U/t, where the RVB state was observed. Owing to the novel discovery of exotic magnetic ordering in triangular moiré patterns in twisted bilayer graphene (TBLG) systems, these results provide insights into the onset of magnetism and the possible spin liquid states in these graphene moiré materials.
Collapse
Affiliation(s)
- Florentino López-Urías
- División de Materiales Avanzados, IPICYT, Camino a la Presa San José 2055, Col Lomas 4a sección, San Luis Potosí S.L.P., 78216, Mexico.
| | - Alberto Rubio-Ponce
- Departamento de Ciencias Básicas, Universidad Autónoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Ciudad de México C.P. 02200, Mexico
| | - Emilio Muñoz-Sandoval
- División de Materiales Avanzados, IPICYT, Camino a la Presa San José 2055, Col Lomas 4a sección, San Luis Potosí S.L.P., 78216, Mexico.
| | - Francisco Sánchez-Ochoa
- Departamento de Materia Condensada, Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, Ciudad de México C.P. 01000, Mexico
| |
Collapse
|
3
|
Ip CIJ, Gao Q, Nguyen KD, Yan C, Yan G, Hoenig E, Marchese TS, Zhang M, Lee W, Rokni H, Meng YS, Liu C, Yang S. Preservation of Topological Surface States in Millimeter-Scale Transferred Membranes. NANO LETTERS 2024. [PMID: 38758657 DOI: 10.1021/acs.nanolett.4c00008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2024]
Abstract
Ultrathin topological insulator membranes are building blocks of exotic quantum matter. However, traditional epitaxy of these materials does not facilitate stacking in arbitrary orders, while mechanical exfoliation from bulk crystals is also challenging due to the non-negligible interlayer coupling therein. Here we liberate millimeter-scale films of the topological insulator Bi2Se3, grown by molecular beam epitaxy, down to 3 quintuple layers. We characterize the preservation of the topological surface states and quantum well states in transferred Bi2Se3 films using angle-resolved photoemission spectroscopy. Leveraging the photon-energy-dependent surface sensitivity, the photoemission spectra taken with 6 and 21.2 eV photons reveal a transfer-induced migration of the topological surface states from the top to the inner layers. By establishing clear electronic structures of the transferred films and unveiling the wave function relocation of the topological surface states, our work lays the physics foundation crucial for the future fabrication of artificially stacked topological materials with single-layer precision.
Collapse
Affiliation(s)
- Chi Ian Jess Ip
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Qiang Gao
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Khanh Duy Nguyen
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Chenhui Yan
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Gangbin Yan
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Eli Hoenig
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Thomas S Marchese
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Minghao Zhang
- Department of NanoEngineering, University of California San Diego, La Jolla, California 92093, United States
| | - Woojoo Lee
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Hossein Rokni
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Ying Shirley Meng
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
- Department of NanoEngineering, University of California San Diego, La Jolla, California 92093, United States
| | - Chong Liu
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Shuolong Yang
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| |
Collapse
|
4
|
Chang C, Zhang X, Li W, Guo Q, Feng Z, Huang C, Ren Y, Cai Y, Zhou X, Wang J, Tang Z, Ding F, Wei W, Liu K, Xu X. Remote epitaxy of single-crystal rhombohedral WS 2 bilayers. Nat Commun 2024; 15:4130. [PMID: 38755189 PMCID: PMC11099013 DOI: 10.1038/s41467-024-48522-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 05/03/2024] [Indexed: 05/18/2024] Open
Abstract
Compared to transition metal dichalcogenide (TMD) monolayers, rhombohedral-stacked (R-stacked) TMD bilayers exhibit remarkable electrical performance, enhanced nonlinear optical response, giant piezo-photovoltaic effect and intrinsic interfacial ferroelectricity. However, from a thermodynamics perspective, the formation energies of R-stacked and hexagonal-stacked (H-stacked) TMD bilayers are nearly identical, leading to mixed stacking of both H- and R-stacked bilayers in epitaxial films. Here, we report the remote epitaxy of centimetre-scale single-crystal R-stacked WS2 bilayer films on sapphire substrates. The bilayer growth is realized by a high flux feeding of the tungsten source at high temperature on substrates. The R-stacked configuration is achieved by the symmetry breaking in a-plane sapphire, where the influence of atomic steps passes through the lower TMD layer and controls the R-stacking of the upper layer. The as-grown R-stacked bilayers show up-to-30-fold enhancements in carrier mobility (34 cm2V-1s-1), nearly doubled circular helicity (61%) and interfacial ferroelectricity, in contrast to monolayer films. Our work reveals a growth mechanism to obtain stacking-controlled bilayer TMD single crystals, and promotes large-scale applications of R-stacked TMD.
Collapse
Affiliation(s)
- Chao Chang
- Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University, Guangzhou, 510006, China
- Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Frontier Research Institute for Physics, South China Normal University, Guangzhou, 510006, China
| | - Xiaowen Zhang
- Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University, Guangzhou, 510006, China
- Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Frontier Research Institute for Physics, South China Normal University, Guangzhou, 510006, China
| | - Weixuan Li
- Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University, Guangzhou, 510006, China
- Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Frontier Research Institute for Physics, South China Normal University, Guangzhou, 510006, China
| | - Quanlin Guo
- State Key Laboratory for Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, 100871, Beijing, China
| | - Zuo Feng
- State Key Laboratory for Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, 100871, Beijing, China
| | - Chen Huang
- State Key Laboratory for Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, 100871, Beijing, China
| | - Yunlong Ren
- Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University, Guangzhou, 510006, China
- Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Frontier Research Institute for Physics, South China Normal University, Guangzhou, 510006, China
- Songshan Lake Materials Laboratory, Institute of Physics, Chinese Academy of Sciences, Dongguan, 523808, China
| | - Yingying Cai
- Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University, Guangzhou, 510006, China
- Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Frontier Research Institute for Physics, South China Normal University, Guangzhou, 510006, China
| | - Xu Zhou
- Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University, Guangzhou, 510006, China
- Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Frontier Research Institute for Physics, South China Normal University, Guangzhou, 510006, China
| | - Jinhuan Wang
- Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University, Guangzhou, 510006, China
- Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Frontier Research Institute for Physics, South China Normal University, Guangzhou, 510006, China
| | - Zhilie Tang
- Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University, Guangzhou, 510006, China
- Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Frontier Research Institute for Physics, South China Normal University, Guangzhou, 510006, China
| | - Feng Ding
- Faculty of Materials Science and Engineering/Institute of Technology for Carbon Neutrality, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Wenya Wei
- Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University, Guangzhou, 510006, China.
- Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Frontier Research Institute for Physics, South China Normal University, Guangzhou, 510006, China.
| | - Kaihui Liu
- State Key Laboratory for Mesoscopic Physics, Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, 100871, Beijing, China.
- Songshan Lake Materials Laboratory, Institute of Physics, Chinese Academy of Sciences, Dongguan, 523808, China.
- Interdisciplinary Institute of Light-Element Quantum Materials and Research Centre for Light-Element Advanced Materials, Peking University, 100871, Beijing, China.
| | - Xiaozhi Xu
- Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University, Guangzhou, 510006, China.
- Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Frontier Research Institute for Physics, South China Normal University, Guangzhou, 510006, China.
| |
Collapse
|
5
|
Zhu X, Sun J, Feng S, Guo H. Moiré band renormalization due to lattice mismatch in bilayer graphene. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:315502. [PMID: 38663420 DOI: 10.1088/1361-648x/ad43a3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 04/25/2024] [Indexed: 05/08/2024]
Abstract
We investigated the band renormalization caused by the compressive-strain-induced lattice mismatch in parallel AA stacked bilayer graphene using two complementary methods: the tight-binding approach and the low-energy continuum theory. While a large mismatch does not alter the low-energy bands, a small one reduces the bandwidth of the low-energy bands along with a decrease in the Fermi velocity. In the tiny-mismatch regime, the low-energy continuum theory reveals that the long-period moiré pattern extensively renormalizes the low-energy bands, resulting in a significant reduction of bandwidth. Meanwhile, the Fermi velocity exhibits an oscillatory behavior and approaches zero at specific mismatches. However, the resulting low-energy bands are not perfectly isolated flat, as seen in twisted bilayer graphene at magic angles. These findings provide a deeper understanding of moiré physics and offer valuable guidance for related experimental studies in creating moiré superlattices using two-dimensional van der Waals heterostructures.
Collapse
Affiliation(s)
- Xingchuan Zhu
- Interdisciplinary Center for Fundamental and Frontier Sciences, Nanjing University of Science and Technology, Jiangyin, Jiangsu 214443, People's Republic of China
| | - Junsong Sun
- School of Physics, Beihang University, Beijing 100191, People's Republic of China
| | - Shiping Feng
- Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Huaiming Guo
- School of Physics, Beihang University, Beijing 100191, People's Republic of China
| |
Collapse
|
6
|
Li H, Xiang Z, Naik MH, Kim W, Li Z, Sailus R, Banerjee R, Taniguchi T, Watanabe K, Tongay S, Zettl A, da Jornada FH, Louie SG, Crommie MF, Wang F. Imaging moiré excited states with photocurrent tunnelling microscopy. NATURE MATERIALS 2024; 23:633-638. [PMID: 38172545 DOI: 10.1038/s41563-023-01753-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 11/06/2023] [Indexed: 01/05/2024]
Abstract
Moiré superlattices provide a highly tuneable and versatile platform to explore novel quantum phases and exotic excited states ranging from correlated insulators to moiré excitons. Scanning tunnelling microscopy has played a key role in probing microscopic behaviours of the moiré correlated ground states at the atomic scale. However, imaging of quantum excited states in moiré heterostructures remains an outstanding challenge. Here we develop a photocurrent tunnelling microscopy technique that combines laser excitation and scanning tunnelling spectroscopy to directly visualize the electron and hole distribution within the photoexcited moiré exciton in twisted bilayer WS2. The tunnelling photocurrent alternates between positive and negative polarities at different locations within a single moiré unit cell. This alternating photocurrent originates from the in-plane charge transfer moiré exciton in twisted bilayer WS2, predicted by our GW-Bethe-Salpeter equation calculations, that emerges from the competition between the electron-hole Coulomb interaction and the moiré potential landscape. Our technique enables the exploration of photoexcited non-equilibrium moiré phenomena at the atomic scale.
Collapse
Affiliation(s)
- Hongyuan Li
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
- Graduate Group in Applied Science and Technology, University of California Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Ziyu Xiang
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
- Graduate Group in Applied Science and Technology, University of California Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Mit H Naik
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Woochang Kim
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Zhenglu Li
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Renee Sailus
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA
| | - Rounak Banerjee
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Sefaattin Tongay
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA
| | - Alex Zettl
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Kavli Energy Nano Sciences Institute, University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Felipe H da Jornada
- Department of Materials Science and Engineering, Stanford University, Palo Alto, CA, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Steven G Louie
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Michael F Crommie
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Kavli Energy Nano Sciences Institute, University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Feng Wang
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Kavli Energy Nano Sciences Institute, University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| |
Collapse
|
7
|
Heo YS, Kim TW, Lee W, Choi J, Park S, Yeom DI, Lee JU. Mesoscopic Stacking Reconfigurations in Stacked van der Waals Film. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2306296. [PMID: 38072812 DOI: 10.1002/smll.202306296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 11/29/2023] [Indexed: 05/25/2024]
Abstract
Mesoscopic-scale stacking reconfigurations are investigated when van der Waals (vdW) films are stacked. A method to visualize complicated stacking structures and mechanical distortions simultaneously in stacked atom-thick films using Raman spectroscopy is developed. In the rigid limit, it is found that the distortions originate from the transfer process, which can be understood through thin film mechanics with a large elastic property mismatch. In contrast, with atomic corrugations, the in-plane strain fields are more closely correlated with the stacking configuration, highlighting the impact of atomic reconstructions on the mesoscopic scale. It is discovered that the grain boundaries do not have a significant effect while the cracks are causing inhomogeneous strain in stacked polycrystalline films. This result contributes to understanding the local variation of emerging properties from moiré structures and advancing the reliability of stacked vdW material fabrication.
Collapse
Affiliation(s)
- Yoon Seong Heo
- Department of Physics and Department of Energy Systems Research, Ajou University, Suwon, 16499, South Korea
| | - Tae Wan Kim
- Department of Physics and Department of Energy Systems Research, Ajou University, Suwon, 16499, South Korea
| | - Wooseok Lee
- Department of Physics and Department of Energy Systems Research, Ajou University, Suwon, 16499, South Korea
| | - Jungseok Choi
- Department of Physics and Department of Energy Systems Research, Ajou University, Suwon, 16499, South Korea
| | - Soyeon Park
- Department of Physics and Department of Energy Systems Research, Ajou University, Suwon, 16499, South Korea
| | - Dong-Il Yeom
- Department of Physics and Department of Energy Systems Research, Ajou University, Suwon, 16499, South Korea
| | - Jae-Ung Lee
- Department of Physics and Department of Energy Systems Research, Ajou University, Suwon, 16499, South Korea
| |
Collapse
|
8
|
Li H, Xiang Z, Regan E, Zhao W, Sailus R, Banerjee R, Taniguchi T, Watanabe K, Tongay S, Zettl A, Crommie MF, Wang F. Mapping charge excitations in generalized Wigner crystals. NATURE NANOTECHNOLOGY 2024; 19:618-623. [PMID: 38286875 DOI: 10.1038/s41565-023-01594-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 12/18/2023] [Indexed: 01/31/2024]
Abstract
Transition metal dichalcogenide-based moiré superlattices exhibit strong electron-electron correlations, thus giving rise to strongly correlated quantum phenomena such as generalized Wigner crystal states. Evidence of Wigner crystals in transition metal dichalcogenide moire superlattices has been widely reported from various optical spectroscopy and electrical conductivity measurements, while their microscopic nature has been limited to the basic lattice structure. Theoretical studies predict that unusual quasiparticle excitations across the correlated gap between upper and lower Hubbard bands can arise due to long-range Coulomb interactions in generalized Wigner crystal states. However, the microscopic proof of such quasiparticle excitations is challenging because of the low excitation energy of the Wigner crystal. Here we describe a scanning single-electron charging spectroscopy technique with nanometre spatial resolution and single-electron charge resolution that enables us to directly image electron and hole wavefunctions and to determine the thermodynamic gap of generalized Wigner crystal states in twisted WS2 moiré heterostructures. High-resolution scanning single-electron charging spectroscopy combines scanning tunnelling microscopy with a monolayer graphene sensing layer, thus enabling the generation of individual electron and hole quasiparticles in generalized Wigner crystals. We show that electron and hole quasiparticles have complementary wavefunction distributions and that thermodynamic gaps of ∼50 meV exist for the 1/3 and 2/3 generalized Wigner crystal states in twisted WS2.
Collapse
Affiliation(s)
- Hongyuan Li
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
- Graduate Group in Applied Science and Technology, University of California at Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Ziyu Xiang
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
- Graduate Group in Applied Science and Technology, University of California at Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Emma Regan
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
- Graduate Group in Applied Science and Technology, University of California at Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Wenyu Zhao
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
| | - Renee Sailus
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA
| | - Rounak Banerjee
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Sefaattin Tongay
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA
| | - Alex Zettl
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Kavli Energy NanoScience Institute at the University of California at Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Michael F Crommie
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Kavli Energy NanoScience Institute at the University of California at Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Feng Wang
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Kavli Energy NanoScience Institute at the University of California at Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| |
Collapse
|
9
|
Foutty BA, Kometter CR, Devakul T, Reddy AP, Watanabe K, Taniguchi T, Fu L, Feldman BE. Mapping twist-tuned multiband topology in bilayer WSe 2. Science 2024; 384:343-347. [PMID: 38669569 DOI: 10.1126/science.adi4728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 03/19/2024] [Indexed: 04/28/2024]
Abstract
Semiconductor moiré superlattices have been shown to host a wide array of interaction-driven ground states. However, twisted homobilayers have been difficult to study in the limit of large moiré wavelengths, where interactions are most dominant. In this study, we conducted local electronic compressibility measurements of twisted bilayer WSe2 (tWSe2) at small twist angles. We demonstrated multiple topological bands that host a series of Chern insulators at zero magnetic field near a "magic angle" around 1.23°. Using a locally applied electric field, we induced a topological quantum-phase transition at one hole per moiré unit cell. Our work establishes the topological phase diagram of a generalized Kane-Mele-Hubbard model in tWSe2, demonstrating a tunable platform for strongly correlated topological phases.
Collapse
Affiliation(s)
- Benjamin A Foutty
- Geballe Laboratory for Advanced Materials, Stanford, CA 94305, USA
- Department of Physics, Stanford University, Stanford, CA 94305, USA
| | - Carlos R Kometter
- Geballe Laboratory for Advanced Materials, Stanford, CA 94305, USA
- Department of Physics, Stanford University, Stanford, CA 94305, USA
| | - Trithep Devakul
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Aidan P Reddy
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Liang Fu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Benjamin E Feldman
- Geballe Laboratory for Advanced Materials, Stanford, CA 94305, USA
- Department of Physics, Stanford University, Stanford, CA 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| |
Collapse
|
10
|
Meneghini G, Brem S, Malic E. Excitonic Thermalization Bottleneck in Twisted TMD Heterostructures. NANO LETTERS 2024; 24:4505-4511. [PMID: 38578047 DOI: 10.1021/acs.nanolett.4c00450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/06/2024]
Abstract
Twisted van der Waals heterostructures show intriguing interface exciton physics, including hybridization effects and emergence of moiré potentials. Recent experiments have revealed that moiré-trapped excitons exhibit remarkable dynamics, where excited states show lifetimes that are several orders of magnitude longer than in monolayers. The origin of this behavior is still under debate. Based on a microscopic many-particle approach, we investigate the phonon-driven relaxation cascade of nonequilibrium moiré excitons in the exemplary MoSe2-WSe2 heterostructure. We track exciton relaxation pathways across different moiré mini-bands and identify the phonon-scattering channels assisting the spatial redistribution of excitons into low-energy pockets of the moiré potential. We unravel a phonon bottleneck in the flat band structure at low twist angles preventing excitons from fully thermalizing into the lowest state, explaining the measured enhanced emission intensity and lifetime of excited moiré excitons. Overall, our work provides important insights into exciton relaxation dynamics in flat-band exciton materials.
Collapse
Affiliation(s)
- Giuseppe Meneghini
- Department of Physics, Philipps University of Marburg, 35037 Marburg, Germany
| | - Samuel Brem
- Department of Physics, Philipps University of Marburg, 35037 Marburg, Germany
| | - Ermin Malic
- Department of Physics, Philipps University of Marburg, 35037 Marburg, Germany
| |
Collapse
|
11
|
Wei L, Xu Q, He Y, Li Q, Huang Y, Zhu W, Watanabe K, Taniguchi T, Claassen M, Rhodes DA, Kennes DM, Xian L, Rubio A, Wang L. Linear resistivity at van Hove singularities in twisted bilayer WSe 2. Proc Natl Acad Sci U S A 2024; 121:e2321665121. [PMID: 38593078 PMCID: PMC11032435 DOI: 10.1073/pnas.2321665121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Accepted: 03/08/2024] [Indexed: 04/11/2024] Open
Abstract
Different mechanisms driving a linear temperature dependence of the resistivity ρ ∼ T at van Hove singularities (VHSs) or metal-insulator transitions when doping a Mott insulator are being debated intensively with competing theoretical proposals. We experimentally investigate this using the exceptional tunability of twisted bilayer (TB) WSe2 by tracking the parameter regions where linear-in-T resistivity is found in dependency of displacement fields, filling, and magnetic fields. We find that even when the VHSs are tuned rather far away from the half-filling point and the Mott insulating transition is absent, the T-linear resistivity persists at the VHSs. When doping away from the VHSs, the T-linear behavior quickly transitions into a Fermi liquid behavior with a T2 relation. No apparent dependency of the linear-in-T resistivity, besides a rather strong change of prefactor, is found when applying displacement fields as long as the filling is tuned to the VHSs, including D ∼ 0.28 V/nm where a high-order VHS is expected. Intriguingly, such non-Fermi liquid linear-in-T resistivity persists even when magnetic fields break the spin-degeneracy of the VHSs at which point two linear in T regions emerge, for each of the split VHSs separately. This points to a mechanism of enhanced scattering at generic VHSs rather than only at high-order VHSs or by a quantum critical point during a Mott transition. Our findings provide insights into the many-body consequences arising out of VHSs, especially the non-Fermi liquid behavior found in moiré materials.
Collapse
Affiliation(s)
- LingNan Wei
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing210093, China
| | - Qiaoling Xu
- Songshan Lake Materials Laboratory, Dongguan, Guangdong523808, China
- College of Physics and Electronic Engineering, Center for Computational Sciences, Sichuan Normal University, Chengdu610068, China
| | - Yangchen He
- Department of Materials Science and Engineering, University of Wisconsin, Madison, WI53706
| | - Qingxin Li
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing210093, China
| | - Yan Huang
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing210093, China
| | - Wang Zhu
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing210093, China
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, Tsukuba305-0044, Japan
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba305-0044, Japan
| | - Martin Claassen
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA19104
| | - Daniel A. Rhodes
- Department of Materials Science and Engineering, University of Wisconsin, Madison, WI53706
| | - Dante M. Kennes
- Institut für Theorie der Statistischen Physik, Rheinisch-Westfälische Technische Hochschule Aachen University and Jülich Aachen Research Alliance-Fundamentals of Future Information Technology, Aachen52056, Germany
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free-Electron Laser Science, Hamburg22761, Germany
| | - Lede Xian
- Songshan Lake Materials Laboratory, Dongguan, Guangdong523808, China
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free-Electron Laser Science, Hamburg22761, Germany
| | - Angel Rubio
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free-Electron Laser Science, Hamburg22761, Germany
- Center for Computational Quantum Physics, Simons Foundation Flatiron Institute, New York, NY10010
| | - Lei Wang
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing210093, China
| |
Collapse
|
12
|
Zhai W, Li Z, Wang Y, Zhai L, Yao Y, Li S, Wang L, Yang H, Chi B, Liang J, Shi Z, Ge Y, Lai Z, Yun Q, Zhang A, Wu Z, He Q, Chen B, Huang Z, Zhang H. Phase Engineering of Nanomaterials: Transition Metal Dichalcogenides. Chem Rev 2024; 124:4479-4539. [PMID: 38552165 DOI: 10.1021/acs.chemrev.3c00931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
Crystal phase, a critical structural characteristic beyond the morphology, size, dimension, facet, etc., determines the physicochemical properties of nanomaterials. As a group of layered nanomaterials with polymorphs, transition metal dichalcogenides (TMDs) have attracted intensive research attention due to their phase-dependent properties. Therefore, great efforts have been devoted to the phase engineering of TMDs to synthesize TMDs with controlled phases, especially unconventional/metastable phases, for various applications in electronics, optoelectronics, catalysis, biomedicine, energy storage and conversion, and ferroelectrics. Considering the significant progress in the synthesis and applications of TMDs, we believe that a comprehensive review on the phase engineering of TMDs is critical to promote their fundamental studies and practical applications. This Review aims to provide a comprehensive introduction and discussion on the crystal structures, synthetic strategies, and phase-dependent properties and applications of TMDs. Finally, our perspectives on the challenges and opportunities in phase engineering of TMDs will also be discussed.
Collapse
Affiliation(s)
- Wei Zhai
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Zijian Li
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Yongji Wang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Li Zhai
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Hong Kong Branch of National Precious Metals Material Engineering Research Center (NPMM), City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Yao Yao
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Siyuan Li
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Lixin Wang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Hua Yang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Banlan Chi
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Jinzhe Liang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Zhenyu Shi
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Yiyao Ge
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China
| | - Zhuangchai Lai
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong 999077, China
| | - Qinbai Yun
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - An Zhang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Zhiying Wu
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Qiyuan He
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Bo Chen
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- State Key Laboratory of Organic Electronics and Information Displays & Jiangsu Key Laboratory for Biosensors, Institute of Advanced Materials (IAM), School of Chemistry and Life Sciences, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
| | - Zhiqi Huang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Hua Zhang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Hong Kong Branch of National Precious Metals Material Engineering Research Center (NPMM), City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Hong Kong Institute for Clean Energy, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Shenzhen Research Institute, City University of Hong Kong, Shenzhen 518057, China
| |
Collapse
|
13
|
Kang K, Shen B, Qiu Y, Zeng Y, Xia Z, Watanabe K, Taniguchi T, Shan J, Mak KF. Evidence of the fractional quantum spin Hall effect in moiré MoTe 2. Nature 2024; 628:522-526. [PMID: 38509375 DOI: 10.1038/s41586-024-07214-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 02/20/2024] [Indexed: 03/22/2024]
Abstract
Quantum spin Hall (QSH) insulators are two-dimensional electronic materials that have a bulk band gap similar to an ordinary insulator but have topologically protected pairs of edge modes of opposite chiralities1-6. So far, experimental studies have found only integer QSH insulators with counter-propagating up-spins and down-spins at each edge leading to a quantized conductance G0 = e2/h (with e and h denoting the electron charge and Planck's constant, respectively)7-14. Here we report transport evidence of a fractional QSH insulator in 2.1° twisted bilayer MoTe2, which supports spin-Sz conservation and flat spin-contrasting Chern bands15,16. At filling factor ν = 3 of the moiré valence bands, each edge contributes a conductance3 2 G 0 with zero anomalous Hall conductivity. The state is probably a time-reversal pair of the even-denominator 3/2-fractional Chern insulators. Furthermore, at ν = 2, 4 and 6, we observe a single, double and triple QSH insulator with each edge contributing a conductance G0, 2G0 and 3G0, respectively. Our results open up the possibility of realizing time-reversal symmetric non-abelian anyons and other unexpected topological phases in highly tunable moiré materials17-19.
Collapse
Affiliation(s)
- Kaifei Kang
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
| | - Bowen Shen
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
| | - Yichen Qiu
- Department of Physics, Cornell University, Ithaca, NY, USA
| | - Yihang Zeng
- Department of Physics, Cornell University, Ithaca, NY, USA
| | - Zhengchao Xia
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
| | - Kenji Watanabe
- National Institute for Materials Science, Tsukuba, Japan
| | | | - Jie Shan
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
- Department of Physics, Cornell University, Ithaca, NY, USA.
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA.
| | - Kin Fai Mak
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
- Department of Physics, Cornell University, Ithaca, NY, USA.
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA.
| |
Collapse
|
14
|
Arsenault EA, Li Y, Yang B, Wang X, Park H, Mosconi E, Ronca E, Taniguchi T, Watanabe K, Gamelin D, Millis A, Dean CR, de Angelis F, Xu X, Zhu XY. Two-Dimensional Moiré Polaronic Electron Crystals. PHYSICAL REVIEW LETTERS 2024; 132:126501. [PMID: 38579228 DOI: 10.1103/physrevlett.132.126501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 02/03/2024] [Accepted: 02/23/2024] [Indexed: 04/07/2024]
Abstract
Two-dimensional moiré materials have emerged as the most versatile platform for realizing quantum phases of electrons. Here, we explore the stability origins of correlated states in WSe_{2}/WS_{2} moiré superlattices. We find that ultrafast electronic excitation leads to partial melting of the Mott states on timescales 5 times longer than predictions from the charge hopping integrals and that the melting rates are thermally activated, with activation energies of 18±3 and 13±2 meV for the one- and two-hole Mott states, respectively, suggesting significant electron-phonon coupling. A density functional theory calculation of the one-hole Mott state confirms polaron formation and yields a hole-polaron binding energy of 16 meV. These findings reveal a close interplay of electron-electron and electron-phonon interactions in stabilizing the polaronic Mott insulators at transition metal dichalcogenide moiré interfaces.
Collapse
Affiliation(s)
- Eric A Arsenault
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Yiliu Li
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Birui Yang
- Department of Physics, Columbia University, New York, New York 10027, USA
| | - Xi Wang
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Heonjoon Park
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
| | - Edoardo Mosconi
- Istituto CNR di Scienze e Tecnologie Chimiche (CNR-SCITEC), CLHYO, 06123 Perugia, Italy
| | - Enrico Ronca
- Department of Chemistry, Biology and Biotechnology, University of Perugia, 06123, Perugia, Italy
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan
| | - Daniel Gamelin
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Andrew Millis
- Department of Physics, Columbia University, New York, New York 10027, USA
| | - Cory R Dean
- Department of Physics, Columbia University, New York, New York 10027, USA
| | - Filippo de Angelis
- Istituto CNR di Scienze e Tecnologie Chimiche (CNR-SCITEC), CLHYO, 06123 Perugia, Italy
- Department of Chemistry, Biology and Biotechnology, University of Perugia, 06123, Perugia, Italy
- Department of Mechanical Engineering, Prince Mohammad Bin Fahd University, Al Khobar, 31952, Saudi Arabia
- SKKU Institute of Energy Science and Technology, Sungkyunkwan University, Suwon, Korea 440-746
| | - Xiaodong Xu
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, USA
| | - X Y Zhu
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| |
Collapse
|
15
|
Wang J, Cheng F, Sun Y, Xu H, Cao L. Stacking engineering in layered homostructures: transitioning from 2D to 3D architectures. Phys Chem Chem Phys 2024; 26:7988-8012. [PMID: 38380525 DOI: 10.1039/d3cp04656g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Artificial materials, characterized by their distinctive properties and customized functionalities, occupy a central role in a wide range of applications including electronics, spintronics, optoelectronics, catalysis, and energy storage. The emergence of atomically thin two-dimensional (2D) materials has driven the creation of artificial heterostructures, harnessing the potential of combining various 2D building blocks with complementary properties through the art of stacking engineering. The promising outcomes achieved for heterostructures have spurred an inquisitive exploration of homostructures, where identical 2D layers are precisely stacked. This perspective primarily focuses on the field of stacking engineering within layered homostructures, where precise control over translational or rotational degrees of freedom between vertically stacked planes or layers is paramount. In particular, we provide an overview of recent advancements in the stacking engineering applied to 2D homostructures. Additionally, we will shed light on research endeavors venturing into three-dimensional (3D) structures, which allow us to proactively address the limitations associated with artificial 2D homostructures. We anticipate that the breakthroughs in stacking engineering in 3D materials will provide valuable insights into the mechanisms governing stacking effects. Such advancements have the potential to unlock the full capability of artificial layered homostructures, propelling the future development of materials, physics, and device applications.
Collapse
Affiliation(s)
- Jiamin Wang
- Changchun Institute of Optics, Fine Mechanics & Physics (CIOMP), Chinese Academy of Sciences, Changchun 130033, P. R. China.
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Fang Cheng
- State Key Laboratory for Organic Electronics and Information Displays & Jiangsu Key Laboratory for Biosensors, Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts and Telecommunications, Nanjing 210023, P. R. China
| | - Yan Sun
- Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, P. R. China.
| | - Hai Xu
- Changchun Institute of Optics, Fine Mechanics & Physics (CIOMP), Chinese Academy of Sciences, Changchun 130033, P. R. China.
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Liang Cao
- Anhui Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei 230031, P. R. China.
| |
Collapse
|
16
|
Yang H, Hu R, Wu H, He X, Zhou Y, Xue Y, He K, Hu W, Chen H, Gong M, Zhang X, Tan PH, Hernández ER, Xie Y. Identification and Structural Characterization of Twisted Atomically Thin Bilayer Materials by Deep Learning. NANO LETTERS 2024; 24:2789-2797. [PMID: 38407030 PMCID: PMC10921996 DOI: 10.1021/acs.nanolett.3c04815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 02/19/2024] [Accepted: 02/20/2024] [Indexed: 02/27/2024]
Abstract
Two-dimensional materials are expected to play an important role in next-generation electronics and optoelectronic devices. Recently, twisted bilayer graphene and transition metal dichalcogenides have attracted significant attention due to their unique physical properties and potential applications. In this study, we describe the use of optical microscopy to collect the color space of chemical vapor deposition (CVD) of molybdenum disulfide (MoS2) and the application of a semantic segmentation convolutional neural network (CNN) to accurately and rapidly identify thicknesses of MoS2 flakes. A second CNN model is trained to provide precise predictions on the twist angle of CVD-grown bilayer flakes. This model harnessed a data set comprising over 10,000 synthetic images, encompassing geometries spanning from hexagonal to triangular shapes. Subsequent validation of the deep learning predictions on twist angles was executed through the second harmonic generation and Raman spectroscopy. Our results introduce a scalable methodology for automated inspection of twisted atomically thin CVD-grown bilayers.
Collapse
Affiliation(s)
- Haitao Yang
- Key
Laboratory of Wide Band-Gap Semiconductor Technology & Shaanxi
Key Laboratory of High-Orbits-Electron Materials and Protection Technology
for Aerospace, School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710071, China
| | - Ruiqi Hu
- Department
of Materials Science and Engineering, University
of Delaware, Newark, Delaware 19716, United States
| | - Heng Wu
- State
Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Xiaolong He
- Key
Laboratory of Wide Band-Gap Semiconductor Technology & Shaanxi
Key Laboratory of High-Orbits-Electron Materials and Protection Technology
for Aerospace, School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710071, China
| | - Yan Zhou
- State
Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Phonon
Engineering Research Center of Jiangsu Province, School of Physics
and Technology, Nanjing Normal University, Nanjing 210023, China
| | - Yizhe Xue
- Key
Laboratory of Wide Band-Gap Semiconductor Technology & Shaanxi
Key Laboratory of High-Orbits-Electron Materials and Protection Technology
for Aerospace, School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710071, China
| | - Kexin He
- Key
Laboratory of Wide Band-Gap Semiconductor Technology & Shaanxi
Key Laboratory of High-Orbits-Electron Materials and Protection Technology
for Aerospace, School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710071, China
| | - Wenshuai Hu
- Key
Laboratory of Wide Band-Gap Semiconductor Technology & Shaanxi
Key Laboratory of High-Orbits-Electron Materials and Protection Technology
for Aerospace, School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710071, China
| | - Haosen Chen
- Key
Laboratory of Wide Band-Gap Semiconductor Technology & Shaanxi
Key Laboratory of High-Orbits-Electron Materials and Protection Technology
for Aerospace, School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710071, China
| | - Mingming Gong
- School
of Materials Science and Engineering, Northwestern
Polytechnical University, Xi’an 710072, China
| | - Xin Zhang
- State
Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Ping-Heng Tan
- State
Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | | | - Yong Xie
- Key
Laboratory of Wide Band-Gap Semiconductor Technology & Shaanxi
Key Laboratory of High-Orbits-Electron Materials and Protection Technology
for Aerospace, School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710071, China
| |
Collapse
|
17
|
Altman AR, Kundu S, da Jornada FH. Mixed Stochastic-Deterministic Approach for Many-Body Perturbation Theory Calculations. PHYSICAL REVIEW LETTERS 2024; 132:086401. [PMID: 38457735 DOI: 10.1103/physrevlett.132.086401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 08/24/2023] [Accepted: 12/05/2023] [Indexed: 03/10/2024]
Abstract
We present an approach for GW calculations of quasiparticle energies with quasiquadratic scaling by approximating high-energy contributions to the Green's function in its Lehmann representation with effective stochastic vectors. The method is easy to implement without altering the GW code, converges rapidly with stochastic parameters, and treats systems of various dimensionality and screening response. Our calculations on a 5.75° twisted MoS_{2} bilayer show how large-scale GW methods include geometry relaxations and electronic correlations on an equal basis in structurally nontrivial materials.
Collapse
Affiliation(s)
- Aaron R Altman
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
| | - Sudipta Kundu
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
| | - Felipe H da Jornada
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| |
Collapse
|
18
|
Xu C, Li J, Xu Y, Bi Z, Zhang Y. Maximally localized Wannier functions, interaction models, and fractional quantum anomalous Hall effect in twisted bilayer MoTe 2. Proc Natl Acad Sci U S A 2024; 121:e2316749121. [PMID: 38349878 PMCID: PMC10895274 DOI: 10.1073/pnas.2316749121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 01/04/2024] [Indexed: 02/15/2024] Open
Abstract
We investigate the moiré band structures and the strong correlation effects in twisted bilayer MoTe[Formula: see text] for a wide range of twist angles, employing a combination of various techniques. Using large-scale first-principles calculations, we pinpoint realistic continuum modeling parameters, subsequently deriving the maximally localized Wannier functions for the top three moiré bands. Simplifying our model with reasonable assumptions, we obtain a minimal two-band model, encompassing Coulomb repulsion, correlated hopping, and spin exchange. Our minimal interaction models pave the way for further exploration of the rich many-body physics in twisted MoTe[Formula: see text]. Furthermore, we explore the phase diagrams of the system through Hartree-Fock approximation and exact diagonalization (ED). Our two-band ED analysis underscores significant band-mixing effects in this system, which enlarge the optimal twist angle for fractional quantum anomalous Hall states.
Collapse
Affiliation(s)
- Cheng Xu
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996
- Department of Physics, Tsinghua University, Beijing 100084, China
| | - Jiangxu Li
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996
| | - Yong Xu
- Department of Physics, Tsinghua University, Beijing 100084, China
| | - Zhen Bi
- Department of Physics, The Pennsylvania State University, University Park, PA 16802
| | - Yang Zhang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996
- Min H. Kao Department of Electrical Engineering and Computer Science, University of Tennessee, Knoxville, TN 37996
| |
Collapse
|
19
|
Yang Y, Morales MA, Zhang S. Metal-Insulator Transition in a Semiconductor Heterobilayer Model. PHYSICAL REVIEW LETTERS 2024; 132:076503. [PMID: 38427879 DOI: 10.1103/physrevlett.132.076503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 01/17/2024] [Indexed: 03/03/2024]
Abstract
Transition metal dichalcogenide superlattices provide an exciting new platform for exploring and understanding a variety of phases of matter. The moiré continuum Hamiltonian, of two-dimensional jellium in a modulating potential, provides a fundamental model for such systems. Accurate computations with this model are essential for interpreting experimental observations and making predictions for future explorations. In this work, we combine two complementary quantum Monte Carlo (QMC) methods, phaseless auxiliary field quantum Monte Carlo and fixed-phase diffusion Monte Carlo, to study the ground state of this Hamiltonian. We observe a metal-insulator transition between a paramagnet and a 120° Néel ordered state as the moiré potential depth and the interaction strength are varied. We find significant differences from existing results by Hartree-Fock and exact diagonalization studies. In addition, we benchmark density-functional theory, and suggest an optimal hybrid functional which best approximates our QMC results.
Collapse
Affiliation(s)
- Yubo Yang
- Center for Computational Quantum Physics, Flatiron Institute, New York, New York 10010, USA
| | - Miguel A Morales
- Center for Computational Quantum Physics, Flatiron Institute, New York, New York 10010, USA
| | - Shiwei Zhang
- Center for Computational Quantum Physics, Flatiron Institute, New York, New York 10010, USA
| |
Collapse
|
20
|
Polovnikov B, Scherzer J, Misra S, Huang X, Mohl C, Li Z, Göser J, Förste J, Bilgin I, Watanabe K, Taniguchi T, Högele A, Baimuratov AS. Field-Induced Hybridization of Moiré Excitons in MoSe_{2}/WS_{2} Heterobilayers. PHYSICAL REVIEW LETTERS 2024; 132:076902. [PMID: 38427888 DOI: 10.1103/physrevlett.132.076902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 01/19/2024] [Indexed: 03/03/2024]
Abstract
We study experimentally and theoretically the hybridization among intralayer and interlayer moiré excitons in a MoSe_{2}/WS_{2} heterostructure with antiparallel alignment. Using a dual-gate device and cryogenic white light reflectance and narrow-band laser modulation spectroscopy, we subject the moiré excitons in the MoSe_{2}/WS_{2} heterostack to a perpendicular electric field, monitor the field-induced dispersion and hybridization of intralayer and interlayer moiré exciton states, and induce a crossover from type I to type II band alignment. Moreover, we employ perpendicular magnetic fields to map out the dependence of the corresponding exciton Landé g factors on the electric field. Finally, we develop an effective theoretical model combining resonant and nonresonant contributions to moiré potentials to explain the observed phenomenology, and highlight the relevance of interlayer coupling for structures with close energetic band alignment as in MoSe_{2}/WS_{2}.
Collapse
Affiliation(s)
- Borislav Polovnikov
- Fakultät für Physik, Munich Quantum Center, and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, Geschwister-Scholl-Platz 1, 80539 München, Germany
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, 85748 Garching bei München, Germany
| | - Johannes Scherzer
- Fakultät für Physik, Munich Quantum Center, and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, Geschwister-Scholl-Platz 1, 80539 München, Germany
| | - Subhradeep Misra
- Fakultät für Physik, Munich Quantum Center, and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, Geschwister-Scholl-Platz 1, 80539 München, Germany
| | - Xin Huang
- Fakultät für Physik, Munich Quantum Center, and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, Geschwister-Scholl-Platz 1, 80539 München, Germany
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, CAS Key Laboratory of Vacuum Physics, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Christian Mohl
- Fakultät für Physik, Munich Quantum Center, and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, Geschwister-Scholl-Platz 1, 80539 München, Germany
| | - Zhijie Li
- Fakultät für Physik, Munich Quantum Center, and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, Geschwister-Scholl-Platz 1, 80539 München, Germany
| | - Jonas Göser
- Fakultät für Physik, Munich Quantum Center, and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, Geschwister-Scholl-Platz 1, 80539 München, Germany
| | - Jonathan Förste
- Fakultät für Physik, Munich Quantum Center, and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, Geschwister-Scholl-Platz 1, 80539 München, Germany
| | - Ismail Bilgin
- Fakultät für Physik, Munich Quantum Center, and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, Geschwister-Scholl-Platz 1, 80539 München, Germany
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Alexander Högele
- Fakultät für Physik, Munich Quantum Center, and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, Geschwister-Scholl-Platz 1, 80539 München, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstraße 4, 80799 München, Germany
| | - Anvar S Baimuratov
- Fakultät für Physik, Munich Quantum Center, and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, Geschwister-Scholl-Platz 1, 80539 München, Germany
| |
Collapse
|
21
|
Joe AY, Pistunova K, Kaasbjerg K, Wang K, Kim B, Rhodes DA, Taniguchi T, Watanabe K, Hone J, Low T, Jauregui LA, Kim P. Transport Study of Charge-Carrier Scattering in Monolayer WSe_{2}. PHYSICAL REVIEW LETTERS 2024; 132:056303. [PMID: 38364168 DOI: 10.1103/physrevlett.132.056303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 12/04/2023] [Accepted: 12/20/2023] [Indexed: 02/18/2024]
Abstract
Employing flux-grown single crystal WSe_{2}, we report charge-carrier scattering behaviors measured in h-BN encapsulated monolayer field effect transistors. We observe a nonmonotonic change of transport mobility as a function of hole density in the degenerately doped sample, which can be explained by energy dependent scattering amplitude of strong defects calculated using the T-matrix approximation. Utilizing long mean-free path (>500 nm), we also demonstrate the high quality of our electronic devices by showing quantized conductance steps from an electrostatically defined quantum point contact, showing the potential for creating ultrahigh quality quantum optoelectronic devices based on atomically thin semiconductors.
Collapse
Affiliation(s)
- Andrew Y Joe
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Kateryna Pistunova
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | | | - Ke Wang
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Bumho Kim
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA
| | - Daniel A Rhodes
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA
| | | | - Kenji Watanabe
- National Institute for Materials Science, Tsukuba, Japan
| | - James Hone
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA
| | - Tony Low
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Luis A Jauregui
- Department of Physics and Astronomy, The University of California, Irvine, California 92697, USA
| | - Philip Kim
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| |
Collapse
|
22
|
Lin KQ, Faria Junior PE, Hübner R, Ziegler JD, Bauer JM, Buchner F, Florian M, Hofmann F, Watanabe K, Taniguchi T, Fabian J, Steinhoff A, Chernikov A, Bange S, Lupton JM. Ultraviolet interlayer excitons in bilayer WSe 2. NATURE NANOTECHNOLOGY 2024; 19:196-201. [PMID: 38049597 DOI: 10.1038/s41565-023-01544-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 10/15/2023] [Indexed: 12/06/2023]
Abstract
Interlayer excitons in van der Waals heterostructures are fascinating for applications like exciton condensation, excitonic devices and moiré-induced quantum emitters. The study of these charge-transfer states has almost exclusively focused on band edges, limiting the spectral region to the near-infrared regime. Here we explore the above-gap analogues of interlayer excitons in bilayer WSe2 and identify both neutral and charged species emitting in the ultraviolet. Even though the transitions occur far above the band edge, the states remain metastable, exhibiting linewidths as narrow as 1.8 meV. These interlayer high-lying excitations have switchable dipole orientations and hence show prominent Stark splitting. The positive and negative interlayer high-lying trions exhibit significant binding energies of 20-30 meV, allowing for a broad tunability of transitions via electric fields and electrostatic doping. The Stark splitting of these trions serves as a highly accurate, built-in sensor for measuring interlayer electric field strengths, which are exceedingly difficult to quantify otherwise. Such excitonic complexes are further sensitive to the interlayer twist angle and offer opportunities to explore emergent moiré physics under electrical control. Our findings more than double the accessible energy range for applications based on interlayer excitons.
Collapse
Affiliation(s)
- Kai-Qiang Lin
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China.
- Department of Physics, University of Regensburg, Regensburg, Germany.
| | | | - Ruven Hübner
- Institute for Theoretical Physics and Bremen Center for Computational Materials Science, University of Bremen, Bremen, Germany
| | - Jonas D Ziegler
- Institute of Applied Physics and Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, Dresden, Germany
| | - Jonas M Bauer
- Department of Physics, University of Regensburg, Regensburg, Germany
| | - Fabian Buchner
- Department of Physics, University of Regensburg, Regensburg, Germany
| | - Matthias Florian
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, USA
| | - Felix Hofmann
- Department of Physics, University of Regensburg, Regensburg, Germany
| | - Kenji Watanabe
- Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Jaroslav Fabian
- Department of Physics, University of Regensburg, Regensburg, Germany
| | - Alexander Steinhoff
- Institute for Theoretical Physics and Bremen Center for Computational Materials Science, University of Bremen, Bremen, Germany
| | - Alexey Chernikov
- Institute of Applied Physics and Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, Dresden, Germany
| | - Sebastian Bange
- Department of Physics, University of Regensburg, Regensburg, Germany
| | - John M Lupton
- Department of Physics, University of Regensburg, Regensburg, Germany
| |
Collapse
|
23
|
Han T, Lu Z, Scuri G, Sung J, Wang J, Han T, Watanabe K, Taniguchi T, Park H, Ju L. Correlated insulator and Chern insulators in pentalayer rhombohedral-stacked graphene. NATURE NANOTECHNOLOGY 2024; 19:181-187. [PMID: 37798567 DOI: 10.1038/s41565-023-01520-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 09/04/2023] [Indexed: 10/07/2023]
Abstract
Rhombohedral-stacked multilayer graphene hosts a pair of flat bands touching at zero energy, which should give rise to correlated electron phenomena that can be tuned further by an electric field. Moreover, when electron correlation breaks the isospin symmetry, the valley-dependent Berry phase at zero energy may give rise to topologically non-trivial states. Here we measure electron transport through hexagonal boron nitride-encapsulated pentalayer graphene down to 100 mK. We observed a correlated insulating state with resistance at the megaohm level or greater at charge density n = 0 and displacement field D = 0. Tight-binding calculations predict a metallic ground state under these conditions. By increasing D, we observed a Chern insulator state with C = -5 and two other states with C = -3 at a magnetic field of around 1 T. At high D and n, we observed isospin-polarized quarter- and half-metals. Hence, rhombohedral pentalayer graphene exhibits two different types of Fermi-surface instability, one driven by a pair of flat bands touching at zero energy, and one induced by the Stoner mechanism in a single flat band. Our results establish rhombohedral multilayer graphene as a suitable system for exploring intertwined electron correlation and topology phenomena in natural graphitic materials without the need for moiré superlattice engineering.
Collapse
Affiliation(s)
- Tonghang Han
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Zhengguang Lu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Giovanni Scuri
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Jiho Sung
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Jue Wang
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Tianyi Han
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Hongkun Park
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Long Ju
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
| |
Collapse
|
24
|
Saigal N, Wurstbauer U. Excitons stabilize above the band gap in bilayer WSe 2. NATURE NANOTECHNOLOGY 2024; 19:141-142. [PMID: 38110530 DOI: 10.1038/s41565-023-01559-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Affiliation(s)
- Nihit Saigal
- Institute of Physics, University of Münster, Münster, Germany
- Center for Soft Nanoscience (SoN), University of Münster, Münster, Germany
| | - Ursula Wurstbauer
- Institute of Physics, University of Münster, Münster, Germany.
- Center for Soft Nanoscience (SoN), University of Münster, Münster, Germany.
| |
Collapse
|
25
|
Kuang X, Pantaleón Peralta PA, Angel Silva-Guillén J, Yuan S, Guinea F, Zhan Z. Optical properties and plasmons in moiré structures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:173001. [PMID: 38232397 DOI: 10.1088/1361-648x/ad1f8c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 01/17/2024] [Indexed: 01/19/2024]
Abstract
The discoveries of numerous exciting phenomena in twisted bilayer graphene (TBG) are stimulating significant investigations on moiré structures that possess a tunable moiré potential. Optical response can provide insights into the electronic structures and transport phenomena of non-twisted and twisted moiré structures. In this article, we review both experimental and theoretical studies of optical properties such as optical conductivity, dielectric function, non-linear optical response, and plasmons in moiré structures composed of graphene, hexagonal boron nitride (hBN), and/or transition metal dichalcogenides. Firstly, a comprehensive introduction to the widely employed methodology on optical properties is presented. After, moiré potential induced optical conductivity and plasmons in non-twisted structures are reviewed, such as single layer graphene-hBN, bilayer graphene-hBN and graphene-metal moiré heterostructures. Next, recent investigations of twist-angle dependent optical response and plasmons are addressed in twisted moiré structures. Additionally, we discuss how optical properties and plasmons could contribute to the understanding of the many-body effects and superconductivity observed in moiré structures.
Collapse
Affiliation(s)
- Xueheng Kuang
- Yangtze Delta Industrial Innovation Center of Quantum Science and Technology, Suzhou 215000, People's Republic of China
| | | | - Jose Angel Silva-Guillén
- Instituto Madrileño de Estudios Avanzados, IMDEA Nanociencia, Calle Faraday 9, 28049 Madrid, Spain
| | - Shengjun Yuan
- Key Laboratory of Artificial Micro- and Nano-structures of the Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
- Wuhan Institute of Quantum Technology, Wuhan 430206, People's Republic of China
| | - Francisco Guinea
- Instituto Madrileño de Estudios Avanzados, IMDEA Nanociencia, Calle Faraday 9, 28049 Madrid, Spain
- Donostia International Physics Center, Paseo Manuel de Lardizábal 4, 20018 San Sebastián, Spain
| | - Zhen Zhan
- Instituto Madrileño de Estudios Avanzados, IMDEA Nanociencia, Calle Faraday 9, 28049 Madrid, Spain
| |
Collapse
|
26
|
Seifert UFP, Balents L. Spin Polarons and Ferromagnetism in Doped Dilute Moiré-Mott Insulators. PHYSICAL REVIEW LETTERS 2024; 132:046501. [PMID: 38335339 DOI: 10.1103/physrevlett.132.046501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 09/15/2023] [Accepted: 12/15/2023] [Indexed: 02/12/2024]
Abstract
Moiré heterostructures of transition metal dichalcogenides (TMDs) exhibit Mott-insulating behavior both at half filling as well as at fractional fillings, where electronic degrees of freedom form self-organized Wigner crystal states. An open question concerns magnetic states obtained by lifting the pseudospin-1/2 degeneracy of these states at lowest temperatures. While at half filling virtual hopping is expected to induce (weak) antiferromagnetic exchange interactions, these are strongly suppressed when considering dilute filling fractions. We argue that, instead, a small concentration of doped electrons leads to the formation of spin polarons, inducing ferromagnetic order at experimentally relevant temperatures, consistent with recently observed ferromagnetic states in moiré TMD systems. We predict explicit signatures of polaron formation in the magnetization profile.
Collapse
Affiliation(s)
- Urban F P Seifert
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA
| | - Leon Balents
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA
- Canadian Institute for Advanced Research, Toronto, Ontario, M5G 1M1, Canada
| |
Collapse
|
27
|
Dai Y, Zhang Z, Zhao P, Cheng Y. Interlayer-coupling-engineerable flat bands in twisted MoSi 2N 4bilayers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:165501. [PMID: 38211330 DOI: 10.1088/1361-648x/ad1d86] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Accepted: 01/11/2024] [Indexed: 01/13/2024]
Abstract
The two-dimensional layered semiconductor MoSi2N4, which has several advantages including high strength, excellent stability, high hole mobility, and high thermal conductivity, was recently successfully synthesized using chemical vapor deposition. Based on first-principles calculations, we investigate the effects of the twist angle and interlayer distance variation on the electronic properties of twisted bilayer MoSi2N4. The flat bands are absent for twisted bilayer MoSi2N4when the twist angleθis reduced to 3.89°. Taking twisted bilayer MoSi2N4withθof 5.09° as an example, we find that flat bands emerge as the interlayer distance decreases. As the interlayer distance can be effectively modulated by hydrostatic pressure, we propose hydrostatic pressure as a knob for tailoring the flat bands in twisted bilayer MoSi2N4. Our findings provide theoretical support for extending the applications of MoSi2N4in strong correlation physics and superconductivity.
Collapse
Affiliation(s)
- Yang Dai
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, People's Republic of China
| | - Zhineng Zhang
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, People's Republic of China
| | - Puqin Zhao
- School of Physical and Mathematical Sciences, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, People's Republic of China
| | - Yingchun Cheng
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, People's Republic of China
| |
Collapse
|
28
|
Shayeganfar F, Ramazani A, Habibiyan H, Rafiee Diznab M. Terahertz linear/non-linear anomalous Hall conductivity of moiré TMD hetero-nanoribbons as topological valleytronics materials. Sci Rep 2024; 14:1581. [PMID: 38238394 PMCID: PMC10796390 DOI: 10.1038/s41598-024-51721-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 01/09/2024] [Indexed: 01/22/2024] Open
Abstract
Twisted moiré van der Waals heterostructures hold promise to provide a robust quantum simulation platform for strongly correlated materials and realize elusive states of matter such as topological states in the laboratory. We demonstrated that the moiré bands of twisted transition metal dichalcogenide (TMD) hetero-nanoribbons exhibit non-trivial topological order due to the tendency of valence and conduction band states in K valleys to form giant band gaps when spin-orbit coupling (SOC) is taken into account. Among the features of twisted WS[Formula: see text]/MoS[Formula: see text] and WSe[Formula: see text]/MoSe[Formula: see text], we found that the heavy fermions associated with the topological flat bands and the presence of strongly correlated states, enhance anomalous Hall conductivity (AHC) away from the magic angle. By band analysis, we showed that the topmost conduction bands from the ± K-valleys are perfectly flat and carry a spin/valley Chern number. Moreover, we showed that the non-linear anomalous Hall effect in moiré TMD hetero-nanoribbons can be used to manipulate terahertz (THz) radiation. Our findings establish twisted heterostructures of group-VI TMD nanoribbons as a tunable platform for engineering topological valley quantum phases and THz non-linear Hall conductivity.
Collapse
Affiliation(s)
- Farzaneh Shayeganfar
- Department of Physics and Energy Engineering, Amirkabir University of Technology, Tehran, Iran.
| | - Ali Ramazani
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Hamidreza Habibiyan
- Department of Physics and Energy Engineering, Amirkabir University of Technology, Tehran, Iran
| | - Mohammad Rafiee Diznab
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| |
Collapse
|
29
|
Gupta N, Sachin S, Kumari P, Rani S, Ray SJ. Twistronics in two-dimensional transition metal dichalcogenide (TMD)-based van der Waals interface. RSC Adv 2024; 14:2878-2888. [PMID: 38239438 PMCID: PMC10793078 DOI: 10.1039/d3ra06559f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 12/06/2023] [Indexed: 01/22/2024] Open
Abstract
Transition metal dichalcogenides (TMD) based heterostructures have gained significant attention lately because of their distinct physical properties and potential uses in electronics and optoelectronics. In the present work, the effects of twist on the structural, electronic, and optical properties (such as the static dielectric constant, refractive index, extinction coefficient, and absorption coefficient) of vertically stacked TMD heterostructures, namely MoSe2/WSe2, WS2/WSe2, MoSe2/WS2 and MoS2/WSe2, have been systematically studied and a thorough comparison is done among these heterostructures. In addition, the absence of negative frequency in the phonon dispersion curve and a low formation energy confirm the structural and thermodynamical stability of all the proposed TMD heterostructures. The calculations are performed using first-principles-based density functional theory (DFT) method. Beautiful Moiré patterns are formed due to the relative rotation of the layers as a consequence of the superposition of the periodic structures of the TMDs on each other. Twist engineering allows the modulation of bandgaps and a phase change from direct to indirect band gap semiconductors as well. The high optical absorption in the visible range of spectrum makes these twisted heterostructures very promising candidates in photovoltaic applications.
Collapse
Affiliation(s)
- Neelam Gupta
- Department of Physics, Indian Institute of Technology Patna Bihta 801103 India
| | - Saurav Sachin
- Department of Physics, Indian Institute of Technology Patna Bihta 801103 India
| | - Puja Kumari
- Department of Physics, Indian Institute of Technology Patna Bihta 801103 India
| | - Shivani Rani
- Department of Physics, Indian Institute of Technology Patna Bihta 801103 India
| | - Soumya Jyoti Ray
- Department of Physics, Indian Institute of Technology Patna Bihta 801103 India
| |
Collapse
|
30
|
Tscheppe P, Zang J, Klett M, Karakuzu S, Celarier A, Cheng Z, Marianetti CA, Maier TA, Ferrero M, Millis AJ, Schäfer T. Magnetism and metallicity in moiré transition metal dichalcogenides. Proc Natl Acad Sci U S A 2024; 121:e2311486121. [PMID: 38207078 PMCID: PMC10801862 DOI: 10.1073/pnas.2311486121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 12/03/2023] [Indexed: 01/13/2024] Open
Abstract
The ability to control the properties of twisted bilayer transition metal dichalcogenides in situ makes them an ideal platform for investigating the interplay of strong correlations and geometric frustration. Of particular interest are the low energy scales, which make it possible to experimentally access both temperature and magnetic fields that are of the order of the bandwidth or the correlation scale. In this manuscript, we analyze the moiré Hubbard model, believed to describe the low energy physics of an important subclass of the twisted bilayer compounds. We establish its magnetic and the metal-insulator phase diagram for the full range of magnetic fields up to the fully spin-polarized state. We find a rich phase diagram including fully and partially polarized insulating and metallic phases of which we determine the interplay of magnetic order, Zeeman-field, and metallicity, and make connection to recent experiments.
Collapse
Affiliation(s)
- Patrick Tscheppe
- Independent Research Group, Max-Planck-Institut für Festkörperforschung, Stuttgart70569, Germany
- Institut für Theoretische Physik and Center for Quantum Science, Universität Tübingen, Tübingen72076, Germany
| | - Jiawei Zang
- Department of Physics, Columbia University, New York, NY10027
| | - Marcel Klett
- Independent Research Group, Max-Planck-Institut für Festkörperforschung, Stuttgart70569, Germany
| | - Seher Karakuzu
- Center for Computational Quantum Physics, Flatiron Institute, New York, NY10010
| | - Armelle Celarier
- CPHT, CNRS, École Polytechnique, Institut Polytechnique de Paris, Palaiseau91128, France
| | - Zhengqian Cheng
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY10027
| | - Chris A. Marianetti
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY10027
| | - Thomas A. Maier
- Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN37831-6164
| | - Michel Ferrero
- CPHT, CNRS, École Polytechnique, Institut Polytechnique de Paris, Palaiseau91128, France
- Collège de France, Paris75005, France
| | - Andrew J. Millis
- Department of Physics, Columbia University, New York, NY10027
- Center for Computational Quantum Physics, Flatiron Institute, New York, NY10010
| | - Thomas Schäfer
- Independent Research Group, Max-Planck-Institut für Festkörperforschung, Stuttgart70569, Germany
| |
Collapse
|
31
|
Zou X, Li R, Chen Z, Dai Y, Huang B, Niu C. Engineering Gapless Edge States from Antiferromagnetic Chern Homobilayer. NANO LETTERS 2024; 24:450-457. [PMID: 38112315 DOI: 10.1021/acs.nanolett.3c04304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
We put forward that stacked Chern insulators with opposite chiralities offer a strategy to achieve gapless helical edge states in two dimensions. We employ the square lattice as an example and elucidate that the gapless chiral and helical edge states emerge in the monolayer and antiferromagnetically stacked bilayer, characterized by Chern number C = - 1 and spin Chern number C S = - 1 , respectively. Particularly, for a topological phase transition to the normal insulator in the stacked bilayer, a band gap closing and reopening procedure takes place accompanied by helical edge states disappearing, where the Chern insulating phase in the monolayer vanishes at the same time. Moreover, EuO is revealed as a suitable candidate for material realization. This work is not only valuable to the research of the quantum anomalous Hall effect but also offers a favorable platform to realize magnetic topologically insulating materials for spintronics applications.
Collapse
Affiliation(s)
- Xiaorong Zou
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong 250100, China
| | - Runhan Li
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong 250100, China
| | - Zhiqi Chen
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong 250100, China
| | - Ying Dai
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong 250100, China
| | - Baibiao Huang
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong 250100, China
| | - Chengwang Niu
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong 250100, China
| |
Collapse
|
32
|
Yu HM, Sharma S, Agarwal S, Liebman O, Banerjee AS. Carbon Kagome nanotubes-quasi-one-dimensional nanostructures with flat bands. RSC Adv 2024; 14:963-981. [PMID: 38188261 PMCID: PMC10768532 DOI: 10.1039/d3ra06988e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Accepted: 11/29/2023] [Indexed: 01/09/2024] Open
Abstract
In recent years, a number of bulk materials and heterostructures have been explored due their connections with exotic materials phenomena emanating from flat band physics and strong electronic correlation. The possibility of realizing such fascinating material properties in simple realistic nanostructures is particularly exciting, especially as the investigation of exotic states of electronic matter in wire-like geometries is relatively unexplored in the literature. Motivated by these considerations, we introduce in this work carbon Kagome nanotubes (CKNTs)-a new allotrope of carbon formed by rolling up Kagome graphene, and investigate this material using specialized first principles calculations. We identify two principal varieties of CKNTs-armchair and zigzag, and find both varieties to be stable at room temperature, based on ab initio molecular dynamics simulations. CKNTs are metallic and feature dispersionless states (i.e., flat bands) near the Fermi level throughout their Brillouin zone, along with an associated singular peak in the electronic density of states. We calculate the mechanical and electronic response of CKNTs to torsional and axial strains, and show that CKNTs appear to be more mechanically compliant than conventional carbon nanotubes (CNTs). Additionally, we find that the electronic properties of CKNTs undergo significant electronic transitions-with emergent partial flat bands and tilted Dirac points-when twisted. We develop a relatively simple tight-binding model that can explain many of these electronic features. We also discuss possible routes for the synthesis of CKNTs. Overall, CKNTs appear to be unique and striking examples of realistic elemental quasi-one-dimensional materials that may display fascinating material properties due to strong electronic correlation. Distorted CKNTs may provide an interesting nanomaterial platform where flat band physics and chirality induced anomalous transport effects may be studied together.
Collapse
Affiliation(s)
- Husan Ming Yu
- Department of Materials Science and Engineering, University of California Los Angeles CA 90095 USA +1-763-656-7830
| | - Shivam Sharma
- Department of Aerospace Engineering and Mechanics, University of Minnesota Minneapolis MN 55455 USA
| | - Shivang Agarwal
- Department of Electrical and Computer Engineering, University of California Los Angeles CA 90095 USA
| | - Olivia Liebman
- Department of Materials Science and Engineering, University of California Los Angeles CA 90095 USA +1-763-656-7830
| | - Amartya S Banerjee
- Department of Materials Science and Engineering, University of California Los Angeles CA 90095 USA +1-763-656-7830
| |
Collapse
|
33
|
Li Y, Zhang F, Ha VA, Lin YC, Dong C, Gao Q, Liu Z, Liu X, Ryu SH, Kim H, Jozwiak C, Bostwick A, Watanabe K, Taniguchi T, Kousa B, Li X, Rotenberg E, Khalaf E, Robinson JA, Giustino F, Shih CK. Tuning commensurability in twisted van der Waals bilayers. Nature 2024; 625:494-499. [PMID: 38233619 DOI: 10.1038/s41586-023-06904-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Accepted: 11/28/2023] [Indexed: 01/19/2024]
Abstract
Moiré superlattices based on van der Waals bilayers1-4 created at small twist angles lead to a long wavelength pattern with approximate translational symmetry. At large twist angles (θt), moiré patterns are, in general, incommensurate except for a few discrete angles. Here we show that large-angle twisted bilayers offer distinctly different platforms. More specifically, by using twisted tungsten diselenide bilayers, we create the incommensurate dodecagon quasicrystals at θt = 30° and the commensurate moiré crystals at θt = 21.8° and 38.2°. Valley-resolved scanning tunnelling spectroscopy shows disparate behaviours between moiré crystals (with translational symmetry) and quasicrystals (with broken translational symmetry). In particular, the K valley shows rich electronic structures exemplified by the formation of mini-gaps near the valence band maximum. These discoveries demonstrate that bilayers with large twist angles offer a design platform to explore moiré physics beyond those formed with small twist angles.
Collapse
Affiliation(s)
- Yanxing Li
- Department of Physics, The University of Texas at Austin, Austin, TX, USA
| | - Fan Zhang
- Department of Physics, The University of Texas at Austin, Austin, TX, USA
| | - Viet-Anh Ha
- Department of Physics, The University of Texas at Austin, Austin, TX, USA
- Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, TX, USA
| | - Yu-Chuan Lin
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, USA
- Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
| | - Chengye Dong
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, USA
| | - Qiang Gao
- Department of Physics, The University of Texas at Austin, Austin, TX, USA
| | - Zhida Liu
- Department of Physics, The University of Texas at Austin, Austin, TX, USA
| | - Xiaohui Liu
- Department of Physics, The University of Texas at Austin, Austin, TX, USA
| | - Sae Hee Ryu
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Hyunsue Kim
- Department of Physics, The University of Texas at Austin, Austin, TX, USA
| | - Chris Jozwiak
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Aaron Bostwick
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Kenji Watanabe
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Bishoy Kousa
- Department of Physics, The University of Texas at Austin, Austin, TX, USA
| | - Xiaoqin Li
- Department of Physics, The University of Texas at Austin, Austin, TX, USA
| | - Eli Rotenberg
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Eslam Khalaf
- Department of Physics, The University of Texas at Austin, Austin, TX, USA
| | - Joshua A Robinson
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, USA
| | - Feliciano Giustino
- Department of Physics, The University of Texas at Austin, Austin, TX, USA
- Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, TX, USA
| | - Chih-Kang Shih
- Department of Physics, The University of Texas at Austin, Austin, TX, USA.
| |
Collapse
|
34
|
Yao Q, Park JW, Won C, Cheong S, Yeom HW. Kinkless Electronic Junction along 1D Electronic Channel Embedded in a Van Der Waals Layer. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2307831. [PMID: 38059812 PMCID: PMC10797480 DOI: 10.1002/advs.202307831] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 11/13/2023] [Indexed: 12/08/2023]
Abstract
Here, the formation of type-I and type-II electronic junctions with or without any structural discontinuity along a well-defined 1 nm-wide 1D electronic channel within a van der Waals layer is reported. Scanning tunneling microscopy and spectroscopy techniques are employed to investigate the atomic and electronic structure along peculiar domain walls formed on the charge-density-wave phase of 1T-TaS2 . Distinct kinds of abrupt electronic junctions with discontinuities of the band gap along the domain walls are found, some of which even do not have any structural kinks and defects. Density-functional calculations reveal a novel mechanism of the electronic junction formation; they are formed by a kinked domain wall in the layer underneath through substantial electronic interlayer coupling. This work demonstrates that the interlayer electronic coupling can be an effective control knob over nanometer-scale electronic property of 2D atomic monolayers.
Collapse
Affiliation(s)
- Qirong Yao
- Center for Artificial Low Dimensional Electronic SystemsInstitute for Basic Science (IBS)Pohang37673South Korea
| | - Jae Whan Park
- Center for Artificial Low Dimensional Electronic SystemsInstitute for Basic Science (IBS)Pohang37673South Korea
| | - Choongjae Won
- Laboratory for Pohang Emergent MaterialsDepartment of PhysicsPohang University of Science and TechnologyPohang37673South Korea
- Max Plank Pohang University of Science and Technology (POSTECH) Center for Complex Phase MaterialsPohang University of Science and TechnologyPohang37673South Korea
| | - Sang‐Wook Cheong
- Laboratory for Pohang Emergent MaterialsDepartment of PhysicsPohang University of Science and TechnologyPohang37673South Korea
- Max Plank Pohang University of Science and Technology (POSTECH) Center for Complex Phase MaterialsPohang University of Science and TechnologyPohang37673South Korea
- Rutgers Center for Emergent Materials and Department of Physics and AstronomyRutgers UniversityPiscatawayNJ08854‐8019USA
| | - Han Woong Yeom
- Center for Artificial Low Dimensional Electronic SystemsInstitute for Basic Science (IBS)Pohang37673South Korea
- Department of PhysicsPohang University of Science and TechnologyPohang37673South Korea
| |
Collapse
|
35
|
Molino L, Aggarwal L, Maity I, Plumadore R, Lischner J, Luican-Mayer A. Influence of Atomic Relaxations on the Moiré Flat Band Wave Functions in Antiparallel Twisted Bilayer WS 2. NANO LETTERS 2023; 23:11778-11784. [PMID: 38054731 DOI: 10.1021/acs.nanolett.3c03735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Twisting bilayers of transition metal dichalcogenides gives rise to a moiré potential resulting in flat bands with localized wave functions and enhanced correlation effects. In this work, scanning tunneling microscopy is used to image a WS2 bilayer twisted approximately 3° off the antiparallel alignment. Scanning tunneling spectroscopy reveals localized states in the vicinity of the valence band onset, which is observed to occur first in regions with S-on-S Bernal stacking. In contrast, density functional theory calculations on twisted bilayers that have been relaxed in vacuum predict the highest-lying flat valence band to be localized in regions of AA' stacking. However, agreement with experiment is recovered when the calculations are performed on bilayers in which the atomic displacements from the unrelaxed positions have been reduced, reflecting the influence of the substrate and finite temperature. This demonstrates the delicate interplay of atomic relaxations and the electronic structure of twisted bilayer materials.
Collapse
Affiliation(s)
- Laurent Molino
- Department of Physics, University of Ottawa, Ottawa K1N 6X3, Canada
| | - Leena Aggarwal
- Department of Physics, University of Ottawa, Ottawa K1N 6X3, Canada
| | - Indrajit Maity
- Department of Materials, Imperial College London, and Thomas Young Centre for Theory and Simulation of Materials, London SW7 2BP, U.K
| | - Ryan Plumadore
- Department of Physics, University of Ottawa, Ottawa K1N 6X3, Canada
| | - Johannes Lischner
- Department of Materials, Imperial College London, and Thomas Young Centre for Theory and Simulation of Materials, London SW7 2BP, U.K
| | | |
Collapse
|
36
|
Bai Y, Li Y, Liu S, Guo Y, Pack J, Wang J, Dean CR, Hone J, Zhu X. Evidence for Exciton Crystals in a 2D Semiconductor Heterotrilayer. NANO LETTERS 2023; 23:11621-11629. [PMID: 38071655 DOI: 10.1021/acs.nanolett.3c03453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
Two-dimensional (2D) transition metal dichalcogenides (TMDC) and their moiré interfaces have been demonstrated for correlated electron states, including Mott insulators and electron/hole crystals commensurate with moiré superlattices. Here we present spectroscopic evidence for ordered bosons─interlayer exciton crystals in a WSe2/MoSe2/WSe2 trilayer, where the enhanced Coulomb interactions over those in heterobilayers have been predicted to result in exciton ordering. Ordered interlayer excitons in the trilayer are characterized by negligible mobility and by sharper PL peaks persisting to an exciton density of nex ∼ 1012 cm-2, which is an order of magnitude higher than the corresponding limit in the heterobilayer. We present evidence for the predicted quadrupolar exciton crystal and its transitions to dipolar excitons either with increasing nex or by an applied electric field. These ordered interlayer excitons may serve as models for the exploration of quantum phase transitions and quantum coherent phenomena.
Collapse
Affiliation(s)
- Yusong Bai
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Yiliu Li
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Song Liu
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
| | - Yinjie Guo
- Department of Physics and Astronomy, Columbia University, New York, New York 10027, United States
| | - Jordan Pack
- Department of Physics and Astronomy, Columbia University, New York, New York 10027, United States
| | - Jue Wang
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Cory R Dean
- Department of Physics and Astronomy, Columbia University, New York, New York 10027, United States
| | - James Hone
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
| | - Xiaoyang Zhu
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| |
Collapse
|
37
|
Quan J, Chen G, Linhart L, Liu Z, Taniguchi T, Watanabe K, Libisch F, Huang R, Li X. Quantifying Strain in Moiré Superlattice. NANO LETTERS 2023; 23:11510-11516. [PMID: 38085265 DOI: 10.1021/acs.nanolett.3c03115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
In twisted van der Waals (vdW) bilayers, intrinsic strain associated with the moiré superlattice and unintentionally introduced uniaxial strain may be present simultaneously. Both strains are able to lift the degeneracy of the E2g phonon modes in Raman spectra. Because of the different rotation symmetry of the two types of strain, the corresponding Raman intensity exhibits a distinct polarization dependence. We compare a 2.5° twisted MoS2 bilayer, in which the maximal intrinsic moiré strain is anticipated, and a natural MoS2 bilayer with an intentionally introduced uniaxial strain. By analyzing the frequency shift of the E2g doublet and their polarization dependence, we can not only determine the direction of unintentional uniaxial strain in the twisted bilayer but also quantify both strain components. This simple strain characterization method based on far-field Raman spectra will facilitate the studies of electronic properties of moiré superlattices under the influence of combined intrinsic and external strains.
Collapse
Affiliation(s)
- Jiamin Quan
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Ganbin Chen
- Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Lukas Linhart
- Institute for Theoretical Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, 1040 Vienna, Austria
| | - Zhida Liu
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Florian Libisch
- Institute for Theoretical Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, 1040 Vienna, Austria
| | - Rui Huang
- Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Xiaoqin Li
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, United States
| |
Collapse
|
38
|
Wu F, Xu Q, Wang Q, Chu Y, Li L, Tang J, Liu J, Tian J, Ji Y, Liu L, Yuan Y, Huang Z, Zhao J, Zan X, Watanabe K, Taniguchi T, Shi D, Gu G, Xu Y, Xian L, Yang W, Du L, Zhang G. Giant Correlated Gap and Possible Room-Temperature Correlated States in Twisted Bilayer MoS_{2}. PHYSICAL REVIEW LETTERS 2023; 131:256201. [PMID: 38181343 DOI: 10.1103/physrevlett.131.256201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 08/21/2023] [Accepted: 11/21/2023] [Indexed: 01/07/2024]
Abstract
Moiré superlattices have emerged as an exciting condensed-matter quantum simulator for exploring the exotic physics of strong electronic correlations. Notable progress has been witnessed, but such correlated states are achievable usually at low temperatures. Here, we report evidence of possible room-temperature correlated electronic states and layer-hybridized SU(4) model simulator in AB-stacked MoS_{2} homobilayer moiré superlattices. Correlated insulating states at moiré band filling factors v=1, 2, 3 are unambiguously established in twisted bilayer MoS_{2}. Remarkably, the correlated electronic state at v=1 shows a giant correlated gap of ∼126 meV and may persist up to a record-high critical temperature over 285 K. The realization of a possible room-temperature correlated state with a large correlated gap in twisted bilayer MoS_{2} can be understood as the cooperation effects of the stacking-specific atomic reconstruction and the resonantly enhanced interlayer hybridization, which largely amplify the moiré superlattice effects on electronic correlations. Furthermore, extreme large nonlinear Hall responses up to room temperature are uncovered near correlated electronic states, demonstrating the quantum geometry of moiré flat conduction band.
Collapse
Affiliation(s)
- Fanfan Wu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qiaoling Xu
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
- College of Physics and Electronic Engineering, Center for Computational Sciences, Sichuan Normal University, Chengdu 610068, China
| | - Qinqin Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanbang Chu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lu Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jian Tang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jieying Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jinpeng Tian
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yiru Ji
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Le Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yalong Yuan
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhiheng Huang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jiaojiao Zhao
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaozhou Zan
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Dongxia Shi
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Gangxu Gu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yang Xu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lede Xian
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Wei Yang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Luojun Du
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guangyu Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| |
Collapse
|
39
|
Saruta Y, Sugawara K, Oka H, Kawakami T, Kato T, Nakayama K, Souma S, Takahashi T, Fukumura T, Sato T. Moiré-Assisted Realization of Octahedral MoTe 2 Monolayer. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2304461. [PMID: 37867224 DOI: 10.1002/advs.202304461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 08/24/2023] [Indexed: 10/24/2023]
Abstract
A current key challenge in 2D materials is the realization of emergent quantum phenomena in hetero structures via controlling the moiré potential created by the periodicity mismatch between adjacent layers, as highlighted by the discovery of superconductivity in twisted bilayer graphene. Generally, the lattice structure of the original host material remains unchanged even after the moiré superlattice is formed. However, much less attention is paid for the possibility that the moiré potential can also modify the original crystal structure itself. Here, it is demonstrated that octahedral MoTe2 which is unstable in bulk is stabilized in a commensurate MoTe2 /graphene hetero-bilayer due to the moiré potential created between the two layers. It is found that the reconstruction of electronic states via the moiré potential is responsible for this stabilization, as evidenced by the energy-gap opening at the Fermi level observed by angle-resolved photoemission and scanning tunneling spectroscopies. The present results provide a fresh approach to realize novel 2D quantum phases by utilizing the moiré potential.
Collapse
Affiliation(s)
- Yasuaki Saruta
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Katsuaki Sugawara
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan
- Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Tokyo, 102-0076, Japan
| | - Hirofumi Oka
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan
| | - Tappei Kawakami
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Takemi Kato
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Kosuke Nakayama
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
- Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Tokyo, 102-0076, Japan
| | - Seigo Souma
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan
- Center for Science and Innovation in Spintronics (CSIS), Tohoku University, Sendai, 980-8577, Japan
| | - Takashi Takahashi
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Tomoteru Fukumura
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Takafumi Sato
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan
- Center for Science and Innovation in Spintronics (CSIS), Tohoku University, Sendai, 980-8577, Japan
- International Center for Synchrotron Radiation Innovation Smart (SRIS), Tohoku University, Sendai, 980-8577, Japan
- Mathematical Science Center for Co-creative Society (MathCCS), Tohoku University, Sendai, 980-8578, Japan
| |
Collapse
|
40
|
Naumis GG, Herrera SA, Poudel SP, Nakamura H, Barraza-Lopez S. Mechanical, electronic, optical, piezoelectric and ferroic properties of strained graphene and other strained monolayers and multilayers: an update. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2023; 87:016502. [PMID: 37879327 DOI: 10.1088/1361-6633/ad06db] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 10/25/2023] [Indexed: 10/27/2023]
Abstract
This is an update of a previous review (Naumiset al2017Rep. Prog. Phys.80096501). Experimental and theoretical advances for straining graphene and other metallic, insulating, ferroelectric, ferroelastic, ferromagnetic and multiferroic 2D materials were considered. We surveyed (i) methods to induce valley and sublattice polarisation (P) in graphene, (ii) time-dependent strain and its impact on graphene's electronic properties, (iii) the role of local and global strain on superconductivity and other highly correlated and/or topological phases of graphene, (iv) inducing polarisationPon hexagonal boron nitride monolayers via strain, (v) modifying the optoelectronic properties of transition metal dichalcogenide monolayers through strain, (vi) ferroic 2D materials with intrinsic elastic (σ), electric (P) and magnetic (M) polarisation under strain, as well as incipient 2D multiferroics and (vii) moiré bilayers exhibiting flat electronic bands and exotic quantum phase diagrams, and other bilayer or few-layer systems exhibiting ferroic orders tunable by rotations and shear strain. The update features the experimental realisations of a tunable two-dimensional Quantum Spin Hall effect in germanene, of elemental 2D ferroelectric bismuth, and 2D multiferroic NiI2. The document was structured for a discussion of effects taking place in monolayers first, followed by discussions concerning bilayers and few-layers, and it represents an up-to-date overview of exciting and newest developments on the fast-paced field of 2D materials.
Collapse
Affiliation(s)
- Gerardo G Naumis
- Departamento de Sistemas Complejos, Instituto de Física, Universidad Nacional Autónoma de México (UNAM), Apdo. Postal 20-364, CDMX, 01000, Mexico
| | - Saúl A Herrera
- Departamento de Sistemas Complejos, Instituto de Física, Universidad Nacional Autónoma de México (UNAM), Apdo. Postal 20-364, CDMX, 01000, Mexico
| | - Shiva P Poudel
- Department of Physics, University of Arkansas, Fayetteville, AR 72701, United States of America
- MonArk NSF Quantum Foundry, University of Arkansas, Fayetteville, AR 72701, United States of America
| | - Hiro Nakamura
- Department of Physics, University of Arkansas, Fayetteville, AR 72701, United States of America
- MonArk NSF Quantum Foundry, University of Arkansas, Fayetteville, AR 72701, United States of America
| | - Salvador Barraza-Lopez
- Department of Physics, University of Arkansas, Fayetteville, AR 72701, United States of America
- MonArk NSF Quantum Foundry, University of Arkansas, Fayetteville, AR 72701, United States of America
| |
Collapse
|
41
|
Liu Y, Morozovska AN, Ghosh A, Kelley KP, Eliseev EA, Yao J, Liu Y, Kalinin S. Stress and Curvature Effects in Layered 2D Ferroelectric CuInP 2S 6. ACS NANO 2023; 17:22004-22014. [PMID: 37917122 DOI: 10.1021/acsnano.3c08603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
Nanoscale ferroelectric 2D materials offer the opportunity to investigate curvature and strain effects on materials functionalities. Among these, CuInP2S6 (CIPS) has attracted tremendous research interest in recent years due to combination of room temperature ferroelectricity, scalability to a few layers thickness, and ferrielectric properties due to coexistence of 2 polar sublattices. Here, we explore the local curvature and strain effect on polarization in CIPS via piezoresponse force microscopy and spectroscopy. To explain the observed behaviors and decouple the curvature and strain effects in 2D CIPS, we introduce the finite element Landau-Ginzburg-Devonshire model, revealing strong changes in hysteresis characteristics in regions subjected to tensile and compressive strain. The piezoresponse force microscopy (PFM) results show that bending induces ferrielectric domains in CIPS, and the polarization-voltage hysteresis loops differ in bending and nonbending regions. These studies offer insights into the fabrication of curvature-engineered nanoelectronic devices.
Collapse
Affiliation(s)
- Yongtao Liu
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Anna N Morozovska
- Institute of Physics, National Academy of Sciences of Ukraine, 46, pr. Nauky, 03028 Kyiv, Ukraine
| | - Ayana Ghosh
- Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Kyle P Kelley
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Eugene A Eliseev
- Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, 3, Krjijanovskogo, 03142 Kyiv, Ukraine
| | - Jinyuan Yao
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Ying Liu
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Sergei Kalinin
- Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States
| |
Collapse
|
42
|
Ciorciaro L, Smoleński T, Morera I, Kiper N, Hiestand S, Kroner M, Zhang Y, Watanabe K, Taniguchi T, Demler E, İmamoğlu A. Kinetic magnetism in triangular moiré materials. Nature 2023; 623:509-513. [PMID: 37968525 PMCID: PMC10651480 DOI: 10.1038/s41586-023-06633-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 09/12/2023] [Indexed: 11/17/2023]
Abstract
Magnetic properties of materials ranging from conventional ferromagnetic metals to strongly correlated materials such as cuprates originate from Coulomb exchange interactions. The existence of alternate mechanisms for magnetism that could naturally facilitate electrical control has been discussed theoretically1-7, but an experimental demonstration8 in an extended system has been missing. Here we investigate MoSe2/WS2 van der Waals heterostructures in the vicinity of Mott insulator states of electrons forming a frustrated triangular lattice and observe direct evidence of magnetic correlations originating from a kinetic mechanism. By directly measuring electronic magnetization through the strength of the polarization-selective attractive polaron resonance9,10, we find that when the Mott state is electron-doped, the system exhibits ferromagnetic correlations in agreement with the Nagaoka mechanism.
Collapse
Affiliation(s)
- L Ciorciaro
- Institute for Quantum Electronics, ETH Zürich, Zürich, Switzerland
| | - T Smoleński
- Institute for Quantum Electronics, ETH Zürich, Zürich, Switzerland
| | - I Morera
- Departament de Física Quàntica i Astrofísica, Facultat de Física, Universitat de Barcelona, Barcelona, Spain
- Institut de Ciències del Cosmos, Universitat de Barcelona, Barcelona, Spain
| | - N Kiper
- Institute for Quantum Electronics, ETH Zürich, Zürich, Switzerland
| | - S Hiestand
- Institute for Quantum Electronics, ETH Zürich, Zürich, Switzerland
| | - M Kroner
- Institute for Quantum Electronics, ETH Zürich, Zürich, Switzerland
| | - Y Zhang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, USA
- Min H. Kao Department of Electrical Engineering and Computer Science, University of Tennessee, Knoxville, TN, USA
| | - K Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, Tsukuba, Japan
| | - T Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - E Demler
- Institute for Theoretical Physics, ETH Zürich, Zürich, Switzerland
| | - A İmamoğlu
- Institute for Quantum Electronics, ETH Zürich, Zürich, Switzerland.
| |
Collapse
|
43
|
Biswas A, Xu R, Alvarez GA, Zhang J, Christiansen-Salameh J, Puthirath AB, Burns K, Hachtel JA, Li T, Iyengar SA, Gray T, Li C, Zhang X, Kannan H, Elkins J, Pieshkov TS, Vajtai R, Birdwell AG, Neupane MR, Garratt EJ, Ivanov TG, Pate BB, Zhao Y, Zhu H, Tian Z, Rubio A, Ajayan PM. Non-Linear Optics at Twist Interfaces in h-BN/SiC Heterostructures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2304624. [PMID: 37707242 DOI: 10.1002/adma.202304624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 07/24/2023] [Indexed: 09/15/2023]
Abstract
Understanding the emergent electronic structure in twisted atomically thin layers has led to the exciting field of twistronics. However, practical applications of such systems are challenging since the specific angular correlations between the layers must be precisely controlled and the layers have to be single crystalline with uniform atomic ordering. Here, an alternative, simple, and scalable approach is suggested, where nanocrystallinetwo-dimensional (2D) film on 3D substrates yields twisted-interface-dependent properties. Ultrawide-bandgap hexagonal boron nitride (h-BN) thin films are directly grown on high in-plane lattice mismatched wide-bandgap silicon carbide (4H-SiC) substrates to explore the twist-dependent structure-property correlations. Concurrently, nanocrystalline h-BN thin film shows strong non-linear second-harmonic generation and ultra-low cross-plane thermal conductivity at room temperature, which are attributed to the twisted domain edges between van der Waals stacked nanocrystals with random in-plane orientations. First-principles calculations based on time-dependent density functional theory manifest strong even-order optical nonlinearity in twisted h-BN layers. This work unveils that directly deposited 2D nanocrystalline thin film on 3D substrates could provide easily accessible twist-interfaces, therefore enabling a simple and scalable approach to utilize the 2D-twistronics integrated in 3D material devices for next-generation nanotechnology.
Collapse
Affiliation(s)
- Abhijit Biswas
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Rui Xu
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Gustavo A Alvarez
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Jin Zhang
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science, Chaussee 149, 22761, Luruper, Germany
| | | | - Anand B Puthirath
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Kory Burns
- Department of Materials Science & Engineering, University of Virginia, Charlottesville, VA, 22904, USA
| | - Jordan A Hachtel
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Tao Li
- Department of Electrical and Computer Engineering, Rice University, Houston, TX, 77005, USA
| | - Sathvik Ajay Iyengar
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Tia Gray
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Chenxi Li
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Xiang Zhang
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Harikishan Kannan
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Jacob Elkins
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Tymofii S Pieshkov
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
- Applied Physics Graduate Program, Smalley-Curl Institute, Rice University, Houston, TX, 77005, USA
| | - Robert Vajtai
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - A Glen Birdwell
- DEVCOM Army Research Laboratory, RF Devices and Circuits, Adelphi, MD, 20783, USA
| | - Mahesh R Neupane
- DEVCOM Army Research Laboratory, RF Devices and Circuits, Adelphi, MD, 20783, USA
| | - Elias J Garratt
- DEVCOM Army Research Laboratory, RF Devices and Circuits, Adelphi, MD, 20783, USA
| | - Tony G Ivanov
- DEVCOM Army Research Laboratory, RF Devices and Circuits, Adelphi, MD, 20783, USA
| | - Bradford B Pate
- Chemistry Division, Naval Research Laboratory, Washington, D.C., 20375, USA
| | - Yuji Zhao
- Department of Electrical and Computer Engineering, Rice University, Houston, TX, 77005, USA
| | - Hanyu Zhu
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| | - Zhiting Tian
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Angel Rubio
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science, Chaussee 149, 22761, Luruper, Germany
- Center for Computational Quantum Physics (CCQ), Flatiron Institute, New York, NY, 10010, USA
| | - Pulickel M Ajayan
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, 77005, USA
| |
Collapse
|
44
|
Tulyagankhodjaev JA, Shih P, Yu J, Russell JC, Chica DG, Reynoso ME, Su H, Stenor AC, Roy X, Berkelbach TC, Delor M. Room-temperature wavelike exciton transport in a van der Waals superatomic semiconductor. Science 2023; 382:438-442. [PMID: 37883547 DOI: 10.1126/science.adf2698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 09/21/2023] [Indexed: 10/28/2023]
Abstract
The transport of energy and information in semiconductors is limited by scattering between electronic carriers and lattice phonons, resulting in diffusive and lossy transport that curtails all semiconductor technologies. Using Re6Se8Cl2, a van der Waals (vdW) superatomic semiconductor, we demonstrate the formation of acoustic exciton-polarons, an electronic quasiparticle shielded from phonon scattering. We directly imaged polaron transport in Re6Se8Cl2 at room temperature, revealing quasi-ballistic, wavelike propagation sustained for a nanosecond and several micrometers. Shielded polaron transport leads to electronic energy propagation lengths orders of magnitude greater than in other vdW semiconductors, exceeding even silicon over a nanosecond. We propose that, counterintuitively, quasi-flat electronic bands and strong exciton-acoustic phonon coupling are together responsible for the transport properties of Re6Se8Cl2, establishing a path to ballistic room-temperature semiconductors.
Collapse
Affiliation(s)
| | - Petra Shih
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Jessica Yu
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Jake C Russell
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Daniel G Chica
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | | | - Haowen Su
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Athena C Stenor
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Xavier Roy
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | | | - Milan Delor
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| |
Collapse
|
45
|
Zhang Y, Kamiya K, Yamamoto T, Sakano M, Yang X, Masubuchi S, Okazaki S, Shinokita K, Chen T, Aso K, Yamada-Takamura Y, Oshima Y, Watanabe K, Taniguchi T, Matsuda K, Sasagawa T, Ishizaka K, Machida T. Symmetry Engineering in Twisted Bilayer WTe 2. NANO LETTERS 2023; 23:9280-9286. [PMID: 37811843 DOI: 10.1021/acs.nanolett.3c02327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
The fabrication of artificial structures using a twisted van der Waals assembly has been a key technique for recent advancements in the research of two-dimensional (2D) materials. To date, various exotic phenomena have been observed thanks to the modified electron correlation or moiré structure controlled by the twist angle. However, the twisted van der Waals assembly has further potential to modulate the physical properties by controlling the symmetry. In this study, we fabricated twisted bilayer WTe2 and demonstrated that the twist angle successfully controls the spatial inversion symmetry and hence the spin splitting in the band structure. Our results reveal the further potential of a twisted van der Waals assembly, suggesting the feasibility of pursuing new physical phenomena in 2D materials based on the control of symmetry.
Collapse
Affiliation(s)
- Yijin Zhang
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Keisuke Kamiya
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Takato Yamamoto
- Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, Tokyo, 113-8656, Japan
| | - Masato Sakano
- Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, Tokyo, 113-8656, Japan
| | - Xiaohan Yang
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Satoru Masubuchi
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Shota Okazaki
- Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Keisuke Shinokita
- Institute of Advanced Energy, Kyoto University, Kyoto 611-0011, Japan
| | - Tongmin Chen
- School of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan
| | - Kohei Aso
- School of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan
| | - Yukiko Yamada-Takamura
- School of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan
| | - Yoshifumi Oshima
- School of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba 305-0044, Japan
| | - Kazunari Matsuda
- Institute of Advanced Energy, Kyoto University, Kyoto 611-0011, Japan
| | - Takao Sasagawa
- Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Kyoko Ishizaka
- Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, Tokyo, 113-8656, Japan
| | - Tomoki Machida
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| |
Collapse
|
46
|
Sinner A, Pantaleón PA, Guinea F. Strain-Induced Quasi-1D Channels in Twisted Moiré Lattices. PHYSICAL REVIEW LETTERS 2023; 131:166402. [PMID: 37925697 DOI: 10.1103/physrevlett.131.166402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 09/11/2023] [Indexed: 11/07/2023]
Abstract
We study the effects of strain in moiré systems composed of honeycomb lattices. We elucidate the formation of almost perfect one-dimensional moiré patterns in twisted bilayer systems. The formation of such patterns is a consequence of an interplay between twist and strain which gives rise to a collapse of the reciprocal space unit cell. As a criterion for such collapse we find a simple relation between the two quantities and the material specific Poisson ratio. The induced one-dimensional behavior is characterized by two, usually incommensurate, periodicities. Our results offer explanations for the complex patterns of one-dimensional channels observed in low angle twisted bilayer graphene systems and twisted bilayer dicalcogenides. Our findings can be applied to any hexagonal twisted moiré pattern and can be easily extended to other geometries.
Collapse
Affiliation(s)
- Andreas Sinner
- IMDEA Nanoscience, Faraday 9, 28049 Madrid, Spain
- Institute of Physics, University of Opole, 45-052 Opole, Poland
| | | | - Francisco Guinea
- IMDEA Nanoscience, Faraday 9, 28049 Madrid, Spain
- Donostia International Physics Center, Paseo Manuel de Lardizábal 4, 20018 San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48009 Bilbao, Spain
| |
Collapse
|
47
|
Jiao C, Pei S, Wu S, Wang Z, Xia J. Tuning and exploiting interlayer coupling in two-dimensional van der Waals heterostructures. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2023; 86:114503. [PMID: 37774692 DOI: 10.1088/1361-6633/acfe89] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Accepted: 09/29/2023] [Indexed: 10/01/2023]
Abstract
Two-dimensional (2D) layered materials can stack into new material systems, with van der Waals (vdW) interaction between the adjacent constituent layers. This stacking process of 2D atomic layers creates a new degree of freedom-interlayer interface between two adjacent layers-that can be independently studied and tuned from the intralayer degree of freedom. In such heterostructures (HSs), the physical properties are largely determined by the vdW interaction between the individual layers,i.e.interlayer coupling, which can be effectively tuned by a number of means. In this review, we summarize and discuss a number of such approaches, including stacking order, electric field, intercalation, and pressure, with both their experimental demonstrations and theoretical predictions. A comprehensive overview of the modulation on structural, optical, electrical, and magnetic properties by these four approaches are also presented. We conclude this review by discussing several prospective research directions in 2D HSs field, including fundamental physics study, property tuning techniques, and future applications.
Collapse
Affiliation(s)
- Chenyin Jiao
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, People's Republic of China
| | - Shenghai Pei
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, People's Republic of China
| | - Song Wu
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, People's Republic of China
| | - Zenghui Wang
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, People's Republic of China
| | - Juan Xia
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, People's Republic of China
| |
Collapse
|
48
|
Baek JH, Kim HG, Lim SY, Hong SC, Chang Y, Ryu H, Jung Y, Jang H, Kim J, Zhang Y, Watanabe K, Taniguchi T, Huang PY, Cheong H, Kim M, Lee GH. Thermally induced atomic reconstruction into fully commensurate structures of transition metal dichalcogenide layers. NATURE MATERIALS 2023:10.1038/s41563-023-01690-2. [PMID: 37828101 DOI: 10.1038/s41563-023-01690-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 09/13/2023] [Indexed: 10/14/2023]
Abstract
Twist angle between two-dimensional layers is a critical parameter that determines their interfacial properties, such as moiré excitons and interfacial ferro-electricity. To achieve better control over these properties for fundamental studies and various applications, considerable efforts have been made to manipulate twist angle. However, due to mechanical limitations and the inevitable formation of incommensurate regions, there remains a challenge in attaining perfect alignment of crystalline orientation. Here we report a thermally induced atomic reconstruction of randomly stacked transition metal dichalcogenide multilayers into fully commensurate heterostructures with zero twist angle by encapsulation annealing, regardless of twist angles of as-stacked samples and lattice mismatches. We also demonstrate the selective formation of R- and H-type fully commensurate phases with a seamless lateral junction using chemical vapour-deposited transition metal dichalcogenides. The resulting fully commensurate phases exhibit strong photoluminescence enhancement of the interlayer excitons, even at room temperature, due to their commensurate structure with aligned momentum coordinates. Our work not only demonstrates a way to fabricate zero-twisted, two-dimensional bilayers with R- and H-type configurations, but also provides a platform for studying their unexplored properties.
Collapse
Affiliation(s)
- Ji-Hwan Baek
- Department of Material Science and Engineering, Seoul National University, Seoul, Korea
| | - Hyoung Gyun Kim
- Department of Material Science and Engineering, Seoul National University, Seoul, Korea
| | - Soo Yeon Lim
- Department of Physics, Sogang University, Seoul, Korea
| | - Seong Chul Hong
- Department of Material Science and Engineering, Seoul National University, Seoul, Korea
| | - Yunyeong Chang
- Department of Material Science and Engineering, Seoul National University, Seoul, Korea
| | - Huije Ryu
- Department of Material Science and Engineering, Seoul National University, Seoul, Korea
| | - Yeonjoon Jung
- Department of Material Science and Engineering, Seoul National University, Seoul, Korea
| | - Hajung Jang
- Department of Physics, Sogang University, Seoul, Korea
| | - Jungcheol Kim
- Department of Physics, Sogang University, Seoul, Korea
| | - Yichao Zhang
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana-Champaign, IL, USA
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Pinshane Y Huang
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana-Champaign, IL, USA
| | | | - Miyoung Kim
- Department of Material Science and Engineering, Seoul National University, Seoul, Korea
| | - Gwan-Hyoung Lee
- Department of Material Science and Engineering, Seoul National University, Seoul, Korea.
| |
Collapse
|
49
|
Kim D, Pandey J, Jeong J, Cho W, Lee S, Cho S, Yang H. Phase Engineering of 2D Materials. Chem Rev 2023; 123:11230-11268. [PMID: 37589590 DOI: 10.1021/acs.chemrev.3c00132] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/18/2023]
Abstract
Polymorphic 2D materials allow structural and electronic phase engineering, which can be used to realize energy-efficient, cost-effective, and scalable device applications. The phase engineering covers not only conventional structural and metal-insulator transitions but also magnetic states, strongly correlated band structures, and topological phases in rich 2D materials. The methods used for the local phase engineering of 2D materials include various optical, geometrical, and chemical processes as well as traditional thermodynamic approaches. In this Review, we survey the precise manipulation of local phases and phase patterning of 2D materials, particularly with ideal and versatile phase interfaces for electronic and energy device applications. Polymorphic 2D materials and diverse quantum materials with their layered, vertical, and lateral geometries are discussed with an emphasis on the role and use of their phase interfaces. Various phase interfaces have demonstrated superior and unique performance in electronic and energy devices. The phase patterning leads to novel homo- and heterojunction structures of 2D materials with low-dimensional phase boundaries, which highlights their potential for technological breakthroughs in future electronic, quantum, and energy devices. Accordingly, we encourage researchers to investigate and exploit phase patterning in emerging 2D materials.
Collapse
Affiliation(s)
- Dohyun Kim
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Juhi Pandey
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Juyeong Jeong
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Woohyun Cho
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Seungyeon Lee
- Division of Chemical Engineering and Materials Science, Graduate Program in System Health Science and Engineering, Ewha Womans University, Seoul 03760, Korea
| | - Suyeon Cho
- Division of Chemical Engineering and Materials Science, Graduate Program in System Health Science and Engineering, Ewha Womans University, Seoul 03760, Korea
| | - Heejun Yang
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| |
Collapse
|
50
|
Pimenta Martins LG, Ruiz-Tijerina DA, Occhialini CA, Park JH, Song Q, Lu AY, Venezuela P, Cançado LG, Mazzoni MSC, Matos MJS, Kong J, Comin R. Pressure tuning of minibands in MoS 2/WSe 2 heterostructures revealed by moiré phonons. NATURE NANOTECHNOLOGY 2023; 18:1147-1153. [PMID: 37322144 DOI: 10.1038/s41565-023-01413-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 05/08/2023] [Indexed: 06/17/2023]
Abstract
Moiré superlattices of two-dimensional heterostructures arose as a new platform to investigate emergent behaviour in quantum solids with unprecedented tunability. To glean insights into the physics of these systems, it is paramount to discover new probes of the moiré potential and moiré minibands, as well as their dependence on external tuning parameters. Hydrostatic pressure is a powerful control parameter, since it allows to continuously and reversibly enhance the moiré potential. Here we use high pressure to tune the minibands in a rotationally aligned MoS2/WSe2 moiré heterostructure, and show that their evolution can be probed via moiré phonons. The latter are Raman-inactive phonons from the individual layers that are activated by the moiré potential. Moiré phonons manifest themselves as satellite Raman peaks arising exclusively from the heterostructure region, increasing in intensity and frequency under applied pressure. Further theoretical analysis reveals that their scattering rate is directly connected to the moiré potential strength. By comparing the experimental and calculated pressure-induced enhancement, we obtain numerical estimates for the moiré potential amplitude and its pressure dependence. The present work establishes moiré phonons as a sensitive probe of the moiré potential as well as the electronic structures of moiré systems.
Collapse
Affiliation(s)
| | - David A Ruiz-Tijerina
- Departamento de Física Química, Instituto de Física, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Connor A Occhialini
- Physics Department, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ji-Hoon Park
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Qian Song
- Physics Department, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ang-Yu Lu
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Pedro Venezuela
- Instituto de Física, Universidade Federal Fluminense, Niterói, Brazil
| | - Luiz G Cançado
- Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Mário S C Mazzoni
- Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Matheus J S Matos
- Departamento de Física, Universidade Federal de Ouro Preto, Ouro Preto, Brazil
| | - Jing Kong
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Riccardo Comin
- Physics Department, Massachusetts Institute of Technology, Cambridge, MA, USA.
| |
Collapse
|