1
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Torbatian Z, Novko D. Plasmon Excitations across the Charge-Density-Wave Transition in Single-Layer TiSe 2. J Phys Chem Lett 2024; 15:6045-6050. [PMID: 38819234 DOI: 10.1021/acs.jpclett.4c01034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
1T-TiSe2 is believed to possess a soft electronic mode, i.e., plasmon or exciton, that might be responsible for the exciton condensation and charge-density-wave (CDW) transition. Here, we explore collective electronic excitations in single-layer 1T-TiSe2 by using the ab initio electromagnetic linear response and unveil intricate scattering pathways of the two-dimensional (2D) plasmon mode near the CDW phase. We found the dominant role of plasmon-phonon scattering, which in combination with the CDW gap excitations leads to the anomalous temperature dependence of the plasmon line width across the CDW transition. Below the transition temperature TCDW a strong hybridization between the 2D plasmon and CDW excitations is obtained. These optical features are highly tunable due to temperature-dependent CDW-related modifications of electronic structure and electron-phonon coupling and make CDW-bearing systems potentially interesting for applications in optoelectronics and low-loss plasmonics.
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Affiliation(s)
- Zahra Torbatian
- School of Nano Science, Institute for Research in Fundamental Sciences (IPM), 19395-5531 Tehran, Iran
| | - Dino Novko
- Centre for Advanced Laser Techniques, Institute of Physics, 10000 Zagreb, Croatia
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
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2
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Rhee TG, Lam NH, Kim YG, Gu M, Hwang J, Bostwick A, Mo SK, Chun SH, Kim J, Chang YJ, Choi BK. Emergence of two distinct phase transitions in monolayer CoSe 2 on graphene. NANO CONVERGENCE 2024; 11:21. [PMID: 38789878 PMCID: PMC11126552 DOI: 10.1186/s40580-024-00427-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Accepted: 05/09/2024] [Indexed: 05/26/2024]
Abstract
Dimensional modifications play a crucial role in various applications, especially in the context of device miniaturization, giving rise to novel quantum phenomena. The many-body dynamics induced by dimensional modifications, including electron-electron, electron-phonon, electron-magnon and electron-plasmon coupling, are known to significantly affect the atomic and electronic properties of the materials. By reducing the dimensionality of orthorhombic CoSe2 and forming heterostructure with bilayer graphene using molecular beam epitaxy, we unveil the emergence of two types of phase transitions through angle-resolved photoemission spectroscopy and scanning tunneling microscopy measurements. We disclose that the 2 × 1 superstructure is associated with charge density wave induced by Fermi surface nesting, characterized by a transition temperature of 340 K. Additionally, another phase transition at temperature of 160 K based on temperature dependent gap evolution are observed with renormalized electronic structure induced by electron-boson coupling. These discoveries of the electronic and atomic modifications, influenced by electron-electron and electron-boson interactions, underscore that many-body physics play significant roles in understanding low-dimensional properties of non-van der Waals Co-chalcogenides and related heterostructures.
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Affiliation(s)
- Tae Gyu Rhee
- Department of Physics, University of Seoul, Seoul, 02504, Korea
- Department of Smart Cities, University of Seoul, Seoul, 02504, Korea
| | - Nguyen Huu Lam
- Department of Physics, University of Ulsan, Ulsan, 44610, Korea
| | - Yeong Gwang Kim
- Department of Physics, University of Seoul, Seoul, 02504, Korea
- Department of Smart Cities, University of Seoul, Seoul, 02504, Korea
| | - Minseon Gu
- Department of Physics, University of Seoul, Seoul, 02504, Korea
| | - Jinwoong Hwang
- Department of Physics, Institute of Quantum Convergence Technology, Kangwon National University, Chuncheon, 24341, Korea
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Aaron Bostwick
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Seung-Hyun Chun
- Department of Physics, Sejong University, Seoul, 05006, Korea
| | - Jungdae Kim
- Department of Physics, University of Ulsan, Ulsan, 44610, Korea.
| | - Young Jun Chang
- Department of Physics, University of Seoul, Seoul, 02504, Korea.
- Department of Smart Cities, University of Seoul, Seoul, 02504, Korea.
- Department of Intelligent Semiconductor Engineering, University of Seoul, Seoul, 02504, Korea.
| | - Byoung Ki Choi
- Department of Physics, University of Seoul, Seoul, 02504, Korea.
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
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3
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Gao W, Zhi G, Zhou M, Niu T. Growth of Single Crystalline 2D Materials beyond Graphene on Non-metallic Substrates. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2311317. [PMID: 38712469 DOI: 10.1002/smll.202311317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 03/14/2024] [Indexed: 05/08/2024]
Abstract
The advent of 2D materials has ushered in the exploration of their synthesis, characterization and application. While plenty of 2D materials have been synthesized on various metallic substrates, interfacial interaction significantly affects their intrinsic electronic properties. Additionally, the complex transfer process presents further challenges. In this context, experimental efforts are devoted to the direct growth on technologically important semiconductor/insulator substrates. This review aims to uncover the effects of substrate on the growth of 2D materials. The focus is on non-metallic substrate used for epitaxial growth and how this highlights the necessity for phase engineering and advanced characterization at atomic scale. Special attention is paid to monoelemental 2D structures with topological properties. The conclusion is drawn through a discussion of the requirements for integrating 2D materials with current semiconductor-based technology and the unique properties of heterostructures based on 2D materials. Overall, this review describes how 2D materials can be fabricated directly on non-metallic substrates and the exploration of growth mechanism at atomic scale.
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Affiliation(s)
- Wenjin Gao
- Tianmushan Laboratory, Hangzhou, 310023, China
- Hangzhou International Innovation Institute, Beihang University, Hangzhou, 311115, China
- School of Physics, Beihang University, Beijing, 100191, China
| | | | - Miao Zhou
- Tianmushan Laboratory, Hangzhou, 310023, China
- Hangzhou International Innovation Institute, Beihang University, Hangzhou, 311115, China
- School of Physics, Beihang University, Beijing, 100191, China
| | - Tianchao Niu
- Hangzhou International Innovation Institute, Beihang University, Hangzhou, 311115, China
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4
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Du M, He X, Wang D, Jiang Z, Zhao X, Shen J. An NIR-II-enhanced nanozyme to promote wound healing in methicillin-resistant Staphylococcus aureus infections. Acta Biomater 2024; 179:300-312. [PMID: 38518865 DOI: 10.1016/j.actbio.2024.03.014] [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: 11/30/2023] [Revised: 03/11/2024] [Accepted: 03/13/2024] [Indexed: 03/24/2024]
Abstract
Deep tissue bacterial infections, especially methicillin-resistant Staphylococcus aureus (MRSA) infections, pose challenges to clinical therapy due to their low debridement efficiency and relapsing. Molybdenum disulfide (MoS2) is used in the antibacterial field as a classic photothermal agent (NIR-I) with good biocompatibility. However, due to its limited NIR-I tissue penetration ability and single treatment mode, MoS2 has poor therapeutic effects on deep tissue infection. Herein, we prepared a defect-type hybrid 2H-MoS2 nanozyme (MoWS2) using hydrothermal method fabricate the MoWS2 composite, which is a new antibacterial strategy involving photothermal and enzyme catalysis, and further enhances the activity of the nanozyme through overheating. The regulation of 2H-MoS2 defects through tungsten ion doping endows MoWS2 with better near-infrared two-region absorption (NIR-II) and enzyme catalytic performance. Antibacterial activity experiments in vitro have shown that MoWS2 can achieve efficient bactericidal activity and biofilm clearance through hyperthermia and reactive oxygen species (ROS). Deep MRSA infection experiments have shown that MoWS2 rapidly removes bacteria from subcutaneous infected tissues through photothermal therapy (PTT) and chemodynamic therapy (CDT), accelerates the dissipation of abscesses, and promotes the healing of infected wounds. Additionally, the versatile treatment mode of MoWS2 was further confirmed through tissue sectioning and immunofluorescence staining analysis. Overall, these results provide a feasible approach for achieving efficient treatment of deep tissue infections through tungsten ion doping to regulate defective 2H-MoS2. STATEMENT OF SIGNIFICANCE: The photothermal effect of MoS2 nanosheets in the NIR-I (650-900 nm) window in anti-MRSA therapy is considered to be highly reliable and efficient in PTA. However, most of the developed PPT therapies or antimicrobial systems based on PTT therapies developed with 1T-MoS2 have in vivo sterilization temperatures of more than 55°C, which have the risk of damaging the normal tissues of the skin. In this study, we prepared W@MoS2 with a good photothermal effect (36.9%) in the NIR-II window and good peroxidase-like activity. The combined effect of PTT and CDT has a stronger bactericidal effect while avoiding high-temperature damage, which makes the W@MoS2 material more advantageous in terms of antimicrobial effect.
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Affiliation(s)
- Mengxuan Du
- School of Life Science and Engineering, Lanzhou University of Technology, Lanzhou, Gansu 730050, China
| | - Xiaojun He
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
| | - Danyan Wang
- Zhejiang Engineering Research Center for Tissue Repair Materials, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325001, China
| | - Zhengting Jiang
- Zhejiang Engineering Research Center for Tissue Repair Materials, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325001, China
| | - Xiaoliang Zhao
- School of Life Science and Engineering, Lanzhou University of Technology, Lanzhou, Gansu 730050, China.
| | - Jianliang Shen
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China; Zhejiang Engineering Research Center for Tissue Repair Materials, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325001, China.
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5
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Hwang J, Ruan W, Chen Y, Tang S, Crommie MF, Shen ZX, Mo SK. Charge density waves in two-dimensional transition metal dichalcogenides. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2024; 87:044502. [PMID: 38518359 DOI: 10.1088/1361-6633/ad36d3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 03/22/2024] [Indexed: 03/24/2024]
Abstract
Charge density wave (CDW is one of the most ubiquitous electronic orders in quantum materials. While the essential ingredients of CDW order have been extensively studied, a comprehensive microscopic understanding is yet to be reached. Recent research efforts on the CDW phenomena in two-dimensional (2D) materials provide a new pathway toward a deeper understanding of its complexity. This review provides an overview of the CDW orders in 2D with atomically thin transition metal dichalcogenides (TMDCs) as the materials platform. We mainly focus on the electronic structure investigations on the epitaxially grown TMDC samples with angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy as complementary experimental tools. We discuss the possible origins of the 2D CDW, novel quantum states coexisting with them, and exotic types of charge orders that can only be realized in the 2D limit.
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Affiliation(s)
- Jinwoong Hwang
- Department of Physics and Institute of Quantum Convergence Technology, Kangwon National University, Chuncheon 24341, Republic of Korea
| | - Wei Ruan
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200438, People's Republic of China
| | - Yi Chen
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China
- Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, Beijing 100871, People's Republic of China
| | - Shujie Tang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
| | - Michael F Crommie
- Department of Physics, University of California, Berkeley, CA, United States of America
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States of America
- Kavli Energy NanoSciences Institute at the University of California at Berkeley, Berkeley, CA 94720, United States of America
| | - Zhi-Xun Shen
- Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, CA, United States of America
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, United States of America
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 United States of America
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6
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Paliwal U, Tanwar P, Joshi KB. Structural, electronic and thermoelectric properties of monolayer TiSe 2. J Mol Model 2024; 30:80. [PMID: 38386089 DOI: 10.1007/s00894-024-05865-9] [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: 01/12/2024] [Accepted: 02/03/2024] [Indexed: 02/23/2024]
Abstract
CONTEXT AND RESULTS In this work the first-principles calculations of the structural, electronic and thermoelectric properties of monolayer TiSe2 are presented. The optimized lattice parameter of monolayer TiSe2 shows excellent agreement with the experimental value. The computed band structure and density of states calculations predict metallic nature of monolayer TiSe2 with overlapping of 0.44 eV between the lowest conduction band and top valance band at high symmetry point M. The position of pseudogap formed by Ti-3d orbitals near the Fermi level confirms the mechanical stability of monolayer TiSe2. Due to the influence of positive strain (tensile strain), the Ti-Se bond length increases and the layer height decreases. The applied tensile strain changes the metallic nature of TiSe2 into a semiconductor with opening of bandgap. It has also been observed that the positions of conduction band minima and valance band maxima change with strain. The charge analysis shows that charge transfer from Ti to Se atom increases when tensile strain is applied, while an opposite trend is observed with compression. The computed thermoelectric coefficients i.e. Seeback coefficient, power factor and figure of merit are in good agreement with the experimental data. The temperature dependence of these coefficients is also reported. COMPUTATIONAL METHOD The density functional theory based calculations are reported employing the PBE-GGA ansatz using the plane wave-pseudopotential method embodied in the Quantum ESPRESSO package. The self-consistent field calculations are performed over a dense Monkhorst-Pack net of 12 × 12 × 1 k-points. The energy convergence criteria for the self-consistent field calculation were set to 10-6 Ry/atom with a cutoff energy of 90 Ry. The thermoelectric properties are computed by combining the band structure calculations with the Boltzmann transport equation using Boltztrap2 peckage.
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Affiliation(s)
- Uttam Paliwal
- Department of Physics, Jai Narain Vyas University, Jodhpur, 342011, India.
| | - Pradeep Tanwar
- Department of Physics, Jai Narain Vyas University, Jodhpur, 342011, India
| | - K B Joshi
- Department of Physics, ML Sukhadia University, Udaipur, 313001, India
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7
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Antonelli T, Rajan A, Watson MD, Soltani S, Houghton J, Siemann GR, Zivanovic A, Bigi C, Edwards B, King PDC. Controlling the Charge Density Wave Transition in Single-Layer TiTe 2xSe 2(1-x) Alloys by Band Gap Engineering. NANO LETTERS 2024; 24:215-221. [PMID: 38117702 PMCID: PMC10786161 DOI: 10.1021/acs.nanolett.3c03776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 12/13/2023] [Accepted: 12/14/2023] [Indexed: 12/22/2023]
Abstract
Closing the band gap of a semiconductor into a semimetallic state gives a powerful potential route to tune the electronic energy gains that drive collective phases like charge density waves (CDWs) and excitonic insulator states. We explore this approach for the controversial CDW material monolayer (ML) TiSe2 by engineering its narrow band gap to the semimetallic limit of ML-TiTe2. Using molecular beam epitaxy, we demonstrate the growth of ML-TiTe2xSe2(1-x) alloys across the entire compositional range and unveil how the (2 × 2) CDW instability evolves through the normal state semiconductor-semimetal transition via in situ angle-resolved photoemission spectroscopy. Through model electronic structure calculations, we identify how this tunes the relative strength of excitonic and Peierls-like coupling, demonstrating band gap engineering as a powerful method for controlling the microscopic mechanisms underpinning the formation of collective states in two-dimensional materials.
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Affiliation(s)
- Tommaso Antonelli
- SUPA, School of Physics and
AstronomyUniversity of St Andrews, St Andrews KY16 9SS, United Kingdom
| | - Akhil Rajan
- SUPA, School of Physics and
AstronomyUniversity of St Andrews, St Andrews KY16 9SS, United Kingdom
| | - Matthew D. Watson
- SUPA, School of Physics and
AstronomyUniversity of St Andrews, St Andrews KY16 9SS, United Kingdom
| | | | - Joe Houghton
- SUPA, School of Physics and
AstronomyUniversity of St Andrews, St Andrews KY16 9SS, United Kingdom
| | - Gesa-Roxanne Siemann
- SUPA, School of Physics and
AstronomyUniversity of St Andrews, St Andrews KY16 9SS, United Kingdom
| | - Andela Zivanovic
- SUPA, School of Physics and
AstronomyUniversity of St Andrews, St Andrews KY16 9SS, United Kingdom
| | - Chiara Bigi
- SUPA, School of Physics and
AstronomyUniversity of St Andrews, St Andrews KY16 9SS, United Kingdom
| | - Brendan Edwards
- SUPA, School of Physics and
AstronomyUniversity of St Andrews, St Andrews KY16 9SS, United Kingdom
| | - Phil D. C. King
- SUPA, School of Physics and
AstronomyUniversity of St Andrews, St Andrews KY16 9SS, United Kingdom
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8
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Wang X, Wang H, Ma L, Zhang L, Yang Z, Dong D, Chen X, Li H, Guan Y, Zhang B, Chen Q, Shi L, Li H, Qin Z, Tu X, Zhang L, Jia X, Chen J, Kang L, Wu P. Topotactic fabrication of transition metal dichalcogenide superconducting nanocircuits. Nat Commun 2023; 14:4282. [PMID: 37463894 DOI: 10.1038/s41467-023-39997-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 07/07/2023] [Indexed: 07/20/2023] Open
Abstract
Superconducting nanocircuits, which are usually fabricated from superconductor films, are the core of superconducting electronic devices. While emerging transition-metal dichalcogenide superconductors (TMDSCs) with exotic properties show promise for exploiting new superconducting mechanisms and applications, their environmental instability leads to a substantial challenge for the nondestructive preparation of TMDSC nanocircuits. Here, we report a universal strategy to fabricate TMDSC nanopatterns via a topotactic conversion method using prepatterned metals as precursors. Typically, robust NbSe2 meandering nanowires can be controllably manufactured on a wafer scale, by which a superconducting nanowire circuit is principally demonstrated toward potential single photon detection. Moreover, versatile superconducting nanocircuits, e.g., periodical circle/triangle hole arrays and spiral nanowires, can be prepared with selected TMD materials (NbS2, TiSe2, or MoTe2). This work provides a generic approach for fabricating nondestructive TMDSC nanocircuits with precise control, which paves the way for the application of TMDSCs in future electronics.
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Affiliation(s)
- Xiaohan Wang
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, College of Engineering and Applied Science, Nanjing University, Nanjing, 210023, China
| | - Hao Wang
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, College of Engineering and Applied Science, Nanjing University, Nanjing, 210023, China.
- Hefei National Laboratory, Hefei, 230088, China.
| | - Liang Ma
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, College of Engineering and Applied Science, Nanjing University, Nanjing, 210023, China
| | - Labao Zhang
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, College of Engineering and Applied Science, Nanjing University, Nanjing, 210023, China.
- Hefei National Laboratory, Hefei, 230088, China.
| | - Zhuolin Yang
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, College of Engineering and Applied Science, Nanjing University, Nanjing, 210023, China
| | - Daxing Dong
- Department of Applied Physics, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China
| | - Xi Chen
- Department of Physics, Tsinghua University, Beijing, 100084, China
| | - Haochen Li
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, College of Engineering and Applied Science, Nanjing University, Nanjing, 210023, China
| | - Yanqiu Guan
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, College of Engineering and Applied Science, Nanjing University, Nanjing, 210023, China
| | - Biao Zhang
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, College of Engineering and Applied Science, Nanjing University, Nanjing, 210023, China
| | - Qi Chen
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, College of Engineering and Applied Science, Nanjing University, Nanjing, 210023, China
| | - Lili Shi
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, College of Engineering and Applied Science, Nanjing University, Nanjing, 210023, China
| | - Hui Li
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, College of Engineering and Applied Science, Nanjing University, Nanjing, 210023, China
| | - Zhi Qin
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, College of Engineering and Applied Science, Nanjing University, Nanjing, 210023, China
| | - Xuecou Tu
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, College of Engineering and Applied Science, Nanjing University, Nanjing, 210023, China
| | - Lijian Zhang
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, College of Engineering and Applied Science, Nanjing University, Nanjing, 210023, China
| | - Xiaoqing Jia
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, College of Engineering and Applied Science, Nanjing University, Nanjing, 210023, China
- Hefei National Laboratory, Hefei, 230088, China
| | - Jian Chen
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, College of Engineering and Applied Science, Nanjing University, Nanjing, 210023, China
| | - Lin Kang
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, College of Engineering and Applied Science, Nanjing University, Nanjing, 210023, China
- Hefei National Laboratory, Hefei, 230088, China
| | - Peiheng Wu
- Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, College of Engineering and Applied Science, Nanjing University, Nanjing, 210023, China.
- Hefei National Laboratory, Hefei, 230088, China.
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9
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Cha S, Lee G, Lee S, Ryu SH, Sohn Y, An G, Kang C, Kim M, Kim K, Soon A, Kim KS. Order-disorder phase transition driven by interlayer sliding in lead iodides. Nat Commun 2023; 14:1981. [PMID: 37031234 PMCID: PMC10082779 DOI: 10.1038/s41467-023-37740-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 03/28/2023] [Indexed: 04/10/2023] Open
Abstract
A variety of phase transitions have been found in two-dimensional layered materials, but some of their atomic-scale mechanisms are hard to clearly understand. Here, we report the discovery of a phase transition whose mechanism is identified as interlayer sliding in lead iodides, a layered material widely used to synthesize lead halide perovskites. The low-temperature crystal structure of lead iodides is found not 2H polytype as known before, but non-centrosymmetric 4H polytype. This undergoes the order-disorder phase transition characterized by the abrupt spectral broadening of valence bands, taken by angle-resolved photoemission, at the critical temperature of 120 K. It is accompanied by drastic changes in simultaneously taken photocurrent and photoluminescence. The transmission electron microscopy is used to reveal that lead iodide layers stacked in the form of 4H polytype at low temperatures irregularly slide over each other above 120 K, which can be explained by the low energy barrier of only 10.6 meV/atom estimated by first principles calculations. Our findings suggest that interlayer sliding is a key mechanism of the phase transitions in layered materials, which can significantly affect optoelectronic and optical characteristics.
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Affiliation(s)
- Seyeong Cha
- Department of Physics, College of Science, Yonsei University, Seoul, Korea
| | - Giyeok Lee
- Department of Materials Science and Engineering, Yonsei University, Seoul, Korea
| | - Sol Lee
- Department of Physics, College of Science, Yonsei University, Seoul, Korea
| | - Sae Hee Ryu
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Yeongsup Sohn
- Department of Physics, College of Science, Yonsei University, Seoul, Korea
| | - Gijeong An
- Department of Physics, College of Science, Yonsei University, Seoul, Korea
| | - Changmo Kang
- Department of Physics, College of Science, Yonsei University, Seoul, Korea
| | - Minsu Kim
- Department of Physics, College of Science, Yonsei University, Seoul, Korea
| | - Kwanpyo Kim
- Department of Physics, College of Science, Yonsei University, Seoul, Korea
| | - Aloysius Soon
- Department of Materials Science and Engineering, Yonsei University, Seoul, Korea.
| | - Keun Su Kim
- Department of Physics, College of Science, Yonsei University, Seoul, Korea.
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10
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Weng X, David P, Guisset V, Martinelli L, Geaymond O, Coraux J, Renaud G. Superstructures, Commensurations, and Rotation of Single-Layer TaS 2 on Au(111) Induced by Cs Intercalation/Deintercalation. ACS NANO 2023; 17:5459-5471. [PMID: 36912862 DOI: 10.1021/acsnano.2c10655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
We use in situ synchrotron grazing incidence X-ray diffraction and X-ray reflectivity to investigate with high resolution the structure of a two-dimensional single layer of tantalum sulfide grown on a Au(111) surface and its evolution during intercalation by Cs atoms and deintercalation, which decouples and recouples the two materials, respectively. The grown single layer consists of a mixture of TaS2 and its S-depleted version, TaS, both aligned with gold, and forming moirés where 7 (respectively 13) lattice constants of the 2D layer almost perfectly match 8 (respectively 15) substrate lattice constants. Intercalation fully decouples the system by lifting the single layer by ∼370 pm and induces an increase of its lattice parameter by 1-2 picometers. The system gradually evolves, during cycles of intercalation/deintercalation assisted by an H2S atmosphere, toward a final coupled state consisting of the fully stoichiometric TaS2 dichalcogenide whose moiré is found very close to the 7/8 commensurability. The reactive H2S atmosphere appears necessary to achieve full deintercalation, presumably by preventing S depletion and the concomitant strong bonding with the intercalant. The structural quality of the layer improves during the cyclic treatment. In parallel, because they are decoupled from the substrate by the intercalation of cesium, some of the TaS2 flakes rotate by 30°. These produce two additional superlattices with characteristic diffraction patterns of different origins. The first is aligned with gold's high symmetry crystallographic directions and is a commensurate moiré ((6 × 6)-Au(111) coinciding with (3√3 × 3√3)R30°-TaS2). The second is incommensurate and corresponds to a near coincidence of (6 × 6) unit cells of 30°-rotated TaS2 with (4√3 × 4√3)Au(111) surface ones. This structure, which is less coupled to gold, might be related to the ∼(3× 3) charge density wave previously reported even at room temperature in TaS2 grown on noninteracting substrates. A (3 × 3) superstructure of 30°-rotated TaS2 islands is indeed revealed by complementary scanning tunneling microscopy.
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Affiliation(s)
- Xiaorong Weng
- Université Grenoble Alpes, CEA, IRIG/MEM/NRS, 38000 Grenoble, France
| | - Philippe David
- Université Grenoble Alpes, CNRS, Institut NEEL, 38000 Grenoble, France
| | - Valérie Guisset
- Université Grenoble Alpes, CNRS, Institut NEEL, 38000 Grenoble, France
| | - Lucio Martinelli
- Université Grenoble Alpes, CNRS, Institut NEEL, 38000 Grenoble, France
| | - Olivier Geaymond
- Université Grenoble Alpes, CNRS, Institut NEEL, 38000 Grenoble, France
| | - Johann Coraux
- Université Grenoble Alpes, CNRS, Institut NEEL, 38000 Grenoble, France
| | - Gilles Renaud
- Université Grenoble Alpes, CEA, IRIG/MEM/NRS, 38000 Grenoble, France
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11
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Evidence of high-temperature exciton condensation in a two-dimensional semimetal. Nat Commun 2023; 14:994. [PMID: 36813811 PMCID: PMC9946959 DOI: 10.1038/s41467-023-36667-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 02/07/2023] [Indexed: 02/24/2023] Open
Abstract
Electrons and holes can spontaneously form excitons and condense in a semimetal or semiconductor, as predicted decades ago. This type of Bose condensation can happen at much higher temperatures in comparison with dilute atomic gases. Two-dimensional (2D) materials with reduced Coulomb screening around the Fermi level are promising for realizing such a system. Here we report a change in the band structure accompanied by a phase transition at about 180 K in single-layer ZrTe2 based on angle-resolved photoemission spectroscopy (ARPES) measurements. Below the transition temperature, gap opening and development of an ultra-flat band top around the zone center are observed. This gap and the phase transition are rapidly suppressed with extra carrier densities introduced by adding more layers or dopants on the surface. The results suggest the formation of an excitonic insulating ground state in single-layer ZrTe2, and the findings are rationalized by first-principles calculations and a self-consistent mean-field theory. Our study provides evidence for exciton condensation in a 2D semimetal and demonstrates strong dimensionality effects on the formation of intrinsic bound electron-hole pairs in solids.
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12
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Lin D, Ranjbar A, Li X, Huang X, Huang Y, Berger H, Forró L, Watanabe K, Taniguchi T, Belosludov RV, Kühne TD, Ding H, Bahramy MS, Xi X. Axial-Bonding-Driven Dimensionality Effect on the Charge-Density Wave in NbSe 2. NANO LETTERS 2022; 22:9389-9395. [PMID: 36416790 DOI: 10.1021/acs.nanolett.2c03280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
2H-NbSe2 is a prototypical charge-density-wave (CDW) system, exhibiting such a symmetry-breaking quantum ground state in its bulk and down to a single-atomic-layer limit. However, how this state depends on dimensionality and what governs the dimensionality effect remain controversial. Here, we experimentally demonstrate a robust 3 × 3 CDW phase in both freestanding and substrate-supported bilayer NbSe2, far above the bulk transition temperature. We exclude environmental effects and reveal a strong temperature and thickness dependence of Raman intensity from an axially vibrating A1g phonon mode, involving Se ions. Using first-principles calculations, we show that these result from a delicate but profound competition between the intra- and interlayer bonding formed between Se-pz orbitals. Our results suggest the crucial role of Se out-of-plane displacement in driving the CDW distortion, revealing the Se-dominated dimensionality effect and establishing a new perspective on the chemical bonding and mechanical stability in layered CDW materials.
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Affiliation(s)
- Dongjing Lin
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing210093, People's Republic of China
| | - Ahmad Ranjbar
- Dynamics of Condensed Matter and Center for Sustainable Systems Design, Theoretical Chemistry, University of Paderborn, Paderborn33098, Germany
| | - Xiaoxia Li
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing210093, People's Republic of China
| | - Xinyu Huang
- Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing100081, People's Republic of China
| | - Yuan Huang
- Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing100081, People's Republic of China
| | - Helmuth Berger
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, 1015Lausanne, Switzerland
| | - László Forró
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, 1015Lausanne, Switzerland
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba305-0044, Japan
| | | | - Thomas D Kühne
- Dynamics of Condensed Matter and Center for Sustainable Systems Design, Theoretical Chemistry, University of Paderborn, Paderborn33098, Germany
| | - Haifeng Ding
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing210093, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing210093, People's Republic of China
| | - Mohammad Saeed Bahramy
- Department of Physics and Astronomy, The University of Manchester, Oxford Road, ManchesterM13 9PL, United Kingdom
| | - Xiaoxiang Xi
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing210093, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing210093, People's Republic of China
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13
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Unveiling the selenium content effect on the properties of TiSe2±α. J SOLID STATE CHEM 2022. [DOI: 10.1016/j.jssc.2022.123768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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14
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Goodwin ZAH, Fal'ko VI. Moiré modulation of charge density waves. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:494001. [PMID: 36223792 DOI: 10.1088/1361-648x/ac99ca] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 10/12/2022] [Indexed: 06/16/2023]
Abstract
Here we investigate how charge density waves (CDWs), inherent to a monolayer, are effected by creating twisted van der Waals structures. Homobilayers of metallic transition metal dichalcogenides (TMDs), at small twist angles where there is significant atomic reconstruction, are utilised as an example to investigate the interplay between the moiré domain structure and CDWs of different periods. For3×3CDWs, there is no geometric constraint to prevent the CDWs from propagating throughout the moiré structure. Whereas for2×2CDWs, to ensure the CDWs in each layer have the most favourable interactions in the domains, the CDW phase must be destroyed in the connecting domain walls. For3×3CDWs with twist angles close to 180∘, moiré-scale triangular structures can form; while close to 0∘, moiré-scale dimer domains occur. The star-of-David CDW (13×13) is found to host CDWs in the domains only, since there is one low energy stacking configuration, similar to the2×2CDWs. These predictions are offered for experimental verification in twisted bilayer metallic TMDs which host CDWs, and we hope this will stimulate further research on the interplay between the moiré superlattice and CDW phases intrinsic to the comprising 2D materials.
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Affiliation(s)
- Zachary A H Goodwin
- National Graphene Institute, University of Manchester, Booth St. E., Manchester M13 9PL, United Kingdom
- School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Vladimir I Fal'ko
- National Graphene Institute, University of Manchester, Booth St. E., Manchester M13 9PL, United Kingdom
- School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- Henry Royce Institute for Advanced Materials, University of Manchester, Manchester M13 9PL, United Kingdom
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15
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Hwang J, Jin Y, Zhang C, Zhu T, Kim K, Zhong Y, Lee JE, Shen Z, Chen Y, Ruan W, Ryu H, Hwang C, Lee J, Crommie MF, Mo SK, Shen ZX. A Novel 19 $\sqrt {19} $ × 19 $\sqrt {19} $ Superstructure in Epitaxially Grown 1T-TaTe 2. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2204579. [PMID: 35902365 DOI: 10.1002/adma.202204579] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 07/21/2022] [Indexed: 06/15/2023]
Abstract
The spontaneous formation of electronic orders is a crucial element for understanding complex quantum states and engineering heterostructures in 2D materials. A novel 19 $\sqrt {19} $ × 19 $\sqrt {19} $ charge order in few-layer-thick 1T-TaTe2 transition metal dichalcogenide films grown by molecular beam epitaxy, which has not been realized, is report. The photoemission and scanning probe measurements demonstrate that monolayer 1T-TaTe2 exhibits a variety of metastable charge density wave orders, including the 19 $\sqrt {19} $ × 19 $\sqrt {19} $ superstructure, which can be selectively stabilized by controlling the post-growth annealing temperature. Moreover, it is found that only the 19 $\sqrt {19} $ × 19 $\sqrt {19} $ order persists in 1T-TaTe2 films thicker than a monolayer, up to 8 layers. The findings identify the previously unrealized novel electronic order in a much-studied transition metal dichalcogenide and provide a viable route to control it within the epitaxial growth process.
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Affiliation(s)
- Jinwoong Hwang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, Pusan National University, Busan, 46241, South Korea
| | - Yeongrok Jin
- Department of Physics, Pusan National University, Busan, 46241, South Korea
| | - Canxun Zhang
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Kavli Energy NanoScience Institute, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Tiancong Zhu
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Kyoo Kim
- Korea Atomic Energy Research Institute, Daejeon, 34057, South Korea
| | - Yong Zhong
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Ji-Eun Lee
- Department of Physics, Pusan National University, Busan, 46241, South Korea
| | - Zongqi Shen
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Yi Chen
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Wei Ruan
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, Fudan University, Fudan, 200433, China
| | - Hyejin Ryu
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, South Korea
| | - Choongyu Hwang
- Department of Physics, Pusan National University, Busan, 46241, South Korea
- Quantum Matter Core-Facility, Pusan National University, Busan, 46241, South Korea
| | - Jaekwang Lee
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, Pusan National University, Busan, 46241, South Korea
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, South Korea
| | - Michael F Crommie
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Kavli Energy NanoScience Institute, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Zhi-Xun Shen
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Geballe Laboratory for Advanced Materials, Department of Physics and Applied Physics, Stanford University, Menlo Park, CA, 94305, USA
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16
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Cohen-Stead B, Bradley O, Miles C, Batrouni G, Scalettar R, Barros K. Fast and scalable quantum Monte Carlo simulations of electron-phonon models. Phys Rev E 2022; 105:065302. [PMID: 35854479 DOI: 10.1103/physreve.105.065302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 05/31/2022] [Indexed: 06/15/2023]
Abstract
We introduce methodologies for highly scalable quantum Monte Carlo simulations of electron-phonon models, and we report benchmark results for the Holstein model on the square lattice. The determinant quantum Monte Carlo (DQMC) method is a widely used tool for simulating simple electron-phonon models at finite temperatures, but it incurs a computational cost that scales cubically with system size. Alternatively, near-linear scaling with system size can be achieved with the hybrid Monte Carlo (HMC) method and an integral representation of the Fermion determinant. Here, we introduce a collection of methodologies that make such simulations even faster. To combat "stiffness" arising from the bosonic action, we review how Fourier acceleration can be combined with time-step splitting. To overcome phonon sampling barriers associated with strongly bound bipolaron formation, we design global Monte Carlo updates that approximately respect particle-hole symmetry. To accelerate the iterative linear solver, we introduce a preconditioner that becomes exact in the adiabatic limit of infinite atomic mass. Finally, we demonstrate how stochastic measurements can be accelerated using fast Fourier transforms. These methods are all complementary and, combined, may produce multiple orders of magnitude speedup, depending on model details.
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Affiliation(s)
| | - Owen Bradley
- Department of Physics, University of California, Davis, California 95616, USA
| | - Cole Miles
- Department of Physics, Cornell University, Ithaca, New York 14853, USA
| | - George Batrouni
- Université Côte d'Azur, CNRS, Institut de Physique de Nice, (INPHYNI), 06103 Nice, France
- Centre for Quantum Technologies, National University of Singapore, 2 Science Drive 3, 117542 Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore
| | - Richard Scalettar
- Department of Physics, University of California, Davis, California 95616, USA
| | - Kipton Barros
- Theoretical Division and CNLS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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17
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Chowdhury S, Rigosi AF, Hill HM, Briggs A, Newell DB, Berger H, Hight Walker AR, Tavazza F. Influence of Dimensionality on the Charge Density Wave Phase of 2H‐TaSe
2. ADVANCED THEORY AND SIMULATIONS 2022. [DOI: 10.1002/adts.202100329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Sugata Chowdhury
- Department of Physics and Astronomy Howard University Washington DC 20059 USA
| | - Albert F. Rigosi
- National Institute of Standards and Technology Gaithersburg MD 20899 USA
| | - Heather M. Hill
- National Institute of Standards and Technology Gaithersburg MD 20899 USA
| | - Andrew Briggs
- National Institute of Standards and Technology Gaithersburg MD 20899 USA
| | - David B. Newell
- National Institute of Standards and Technology Gaithersburg MD 20899 USA
| | - Helmuth Berger
- École Polytechnique Fédérale de Lausanne (EPFL) Institut de Physique des Nanostructures Lausanne CH‐1015 Switzerland
| | | | - Francesca Tavazza
- National Institute of Standards and Technology Gaithersburg MD 20899 USA
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18
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Huang Z, Song X, Chen Y, Yang H, Yuan P, Ma H, Qiao J, Zhang Y, Sun J, Zhang T, Huang Y, Liu L, Gao HJ, Wang Y. Size Dependence of Charge-Density-Wave Orders in Single-Layer NbSe 2 Hetero/Homophase Junctions. J Phys Chem Lett 2022; 13:1901-1907. [PMID: 35179388 DOI: 10.1021/acs.jpclett.1c04138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Controlling charge-density-wave (CDW) orders in two-dimensional (2D) crystals has attracted a great deal of interest because of their fundamental physics and their demand inse in miniaturized devices. In this work, we systematically studied the size-dependent CDW orders in single-layer hetero/homo-NbSe2 stacking junctions. We found that the CDW orders in the top 1T-NbSe2 layer of the junctions are highly dependent on its lateral size. For the 1T/2H-NbSe2 heterojunction, the critical lateral size of 1T-NbSe2 islands for the formation of well-defined CDW orders is ∼26 nm, whereas below 15 nm, the CDW orders melt. However, for the 1T/1T-NbSe2 homojunction, the CDW orders in the islands can persist even with a lateral size of <11 nm. Our findings illuminate the fresh phenomenon of size-dependent CDW orders existing in 2D van der Waals hetero/homojunctions and provide useful information for the control of CDW orders.
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Affiliation(s)
- Zeping Huang
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
| | - Xuan Song
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
| | - Yaoyao Chen
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
| | - Han Yang
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
| | - Peiwen Yuan
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
| | - Hang Ma
- School of Automation, Beijing Information Science and Technology University, Beijing 100085, China
| | - Jingsi Qiao
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
- Centre for Advanced 2D Materials, National University of Singapore, 117546 Singapore
| | - Yu Zhang
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
| | - Jiatao Sun
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
| | - Teng Zhang
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
| | - Yuan Huang
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
| | - Liwei Liu
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
| | - Hong-Jun Gao
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yeliang Wang
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
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19
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Zhao WM, Zhu L, Nie Z, Li QY, Wang QW, Dou LG, Hu JG, Xian L, Meng S, Li SC. Moiré enhanced charge density wave state in twisted 1T-TiTe 2/1T-TiSe 2 heterostructures. NATURE MATERIALS 2022; 21:284-289. [PMID: 34916657 DOI: 10.1038/s41563-021-01167-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 11/09/2021] [Indexed: 06/14/2023]
Abstract
Nanoscale periodic moiré patterns, for example those formed at the interface of a twisted bilayer of two-dimensional materials, provide opportunities for engineering the electronic properties of van der Waals heterostructures1-11. In this work, we synthesized the epitaxial heterostructure of 1T-TiTe2/1T-TiSe2 with various twist angles using molecular beam epitaxy and investigated the moiré pattern induced/enhanced charge density wave (CDW) states with scanning tunnelling microscopy. When the twist angle is near zero degrees, 2 × 2 CDW domains are formed in 1T-TiTe2, separated by 1 × 1 normal state domains, and trapped in the moiré pattern. The formation of the moiré-trapped CDW state is ascribed to the local strain variation due to atomic reconstruction. Furthermore, this CDW state persists at room temperature, suggesting its potential for future CDW-based applications. Such moiré-trapped CDW patterns were not observed at larger twist angles. Our study paves the way for constructing metallic twist van der Waals bilayers and tuning many-body effects via moiré engineering.
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Affiliation(s)
- Wei-Min Zhao
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Li Zhu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Zhengwei Nie
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, P. R. China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Qi-Yuan Li
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Qi-Wei Wang
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Li-Guo Dou
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Ju-Gang Hu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Lede Xian
- Songshan Lake Materials Laboratory, Dongguan, P. R. China
| | - Sheng Meng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, P. R. China.
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China.
- Songshan Lake Materials Laboratory, Dongguan, P. R. China.
| | - Shao-Chun Li
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, China.
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.
- Jiangsu Provincial Key Laboratory for Nanotechnology, Nanjing University, Nanjing, China.
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20
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Light-induced dimension crossover dictated by excitonic correlations. Nat Commun 2022; 13:963. [PMID: 35181649 PMCID: PMC8857203 DOI: 10.1038/s41467-022-28309-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 01/17/2022] [Indexed: 11/08/2022] Open
Abstract
In low-dimensional systems with strong electronic correlations, the application of an ultrashort laser pulse often yields novel phases that are otherwise inaccessible. The central challenge in understanding such phenomena is to determine how dimensionality and many-body correlations together govern the pathway of a non-adiabatic transition. To this end, we examine a layered compound, 1T-TiSe2, whose three-dimensional charge-density-wave (3D CDW) state also features exciton condensation due to strong electron-hole interactions. We find that photoexcitation suppresses the equilibrium 3D CDW while creating a nonequilibrium 2D CDW. Remarkably, the dimension reduction does not occur unless bound electron-hole pairs are broken. This relation suggests that excitonic correlations maintain the out-of-plane CDW coherence, settling a long-standing debate over their role in the CDW transition. Our findings demonstrate how optical manipulation of electronic interaction enables one to control the dimensionality of a broken-symmetry order, paving the way for realizing other emergent states in strongly correlated systems.
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21
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Computational Methods for Charge Density Waves in 2D Materials. NANOMATERIALS 2022; 12:nano12030504. [PMID: 35159849 PMCID: PMC8839743 DOI: 10.3390/nano12030504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/20/2022] [Accepted: 01/26/2022] [Indexed: 11/29/2022]
Abstract
Two-dimensional (2D) materials that exhibit charge density waves (CDWs)—spontaneous reorganization of their electrons into a periodic modulation—have generated many research endeavors in the hopes of employing their exotic properties for various quantum-based technologies. Early investigations surrounding CDWs were mostly focused on bulk materials. However, applications for quantum devices require few-layer materials to fully utilize the emergent phenomena. The CDW field has greatly expanded over the decades, warranting a focus on the computational efforts surrounding them specifically in 2D materials. In this review, we cover ground in the following relevant theory-driven subtopics for TaS2 and TaSe2: summary of general computational techniques and methods, resulting atomic structures, the effect of electron–phonon interaction of the Raman scattering modes, the effects of confinement and dimensionality on the CDW, and we end with a future outlook. Through understanding how the computational methods have enabled incredible advancements in quantum materials, one may anticipate the ever-expanding directions available for continued pursuit as the field brings us through the 21st century.
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22
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Ren MQ, Han S, Fan JQ, Wang L, Wang P, Ren W, Peng K, Li S, Wang SZ, Zheng FW, Zhang P, Li F, Ma X, Xue QK, Song CL. Semiconductor-Metal Phase Transition and Emergent Charge Density Waves in 1 T-ZrX 2 (X = Se, Te) at the Two-Dimensional Limit. NANO LETTERS 2022; 22:476-484. [PMID: 34978815 DOI: 10.1021/acs.nanolett.1c04372] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A charge density wave (CDW) is a collective quantum phenomenon in metals and features a wavelike modulation of the conduction electron density. A microscopic understanding and experimental control of this many-body electronic state in atomically thin materials remain hot topics in materials physics. By means of material engineering, we realized a dimensionality and Zr intercalation induced semiconductor-metal phase transition in 1T-ZrX2 (X = Se, Te) ultrathin films, accompanied by a commensurate 2 × 2 CDW order. Furthermore, we observed a CDW energy gap of up to 22 meV around the Fermi level. Fourier-transformed scanning tunneling microscopy and angle-resolved photoemission spectroscopy reveal that 1T-ZrX2 films exhibit the simplest Fermi surface among the known CDW materials in TMDCs, consisting only of a Zr 4d derived elliptical electron conduction band at the corners of the Brillouin zone.
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Affiliation(s)
- Ming-Qiang Ren
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Sha Han
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Jia-Qi Fan
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Li Wang
- Vacuum Interconnected Nanotech Workstation, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, People's Republic of China
| | - Pengdong Wang
- Vacuum Interconnected Nanotech Workstation, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, People's Republic of China
| | - Wei Ren
- Vacuum Interconnected Nanotech Workstation, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, People's Republic of China
| | - Kun Peng
- Vacuum Interconnected Nanotech Workstation, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, People's Republic of China
| | - Shujing Li
- College of Mathematics and Physics, Beijing University of Chemical Technology, Beijing 100029, People's Republic of China
| | - Shu-Ze Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Fa-Wei Zheng
- Institute of Applied Physics and Computational Mathematics, Beijing 100088, People's Republic of China
| | - Ping Zhang
- College of Mathematics and Physics, Beijing University of Chemical Technology, Beijing 100029, People's Republic of China
| | - Fangsen Li
- Vacuum Interconnected Nanotech Workstation, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, People's Republic of China
| | - Xucun Ma
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
- Frontier Science Center for Quantum Information, Beijing 100084, People's Republic of China
| | - Qi-Kun Xue
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
- Frontier Science Center for Quantum Information, Beijing 100084, People's Republic of China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, People's Republic of China
| | - Can-Li Song
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
- Frontier Science Center for Quantum Information, Beijing 100084, People's Republic of China
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23
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Dreher P, Wan W, Chikina A, Bianchi M, Guo H, Harsh R, Mañas-Valero S, Coronado E, Martínez-Galera AJ, Hofmann P, Miwa JA, Ugeda MM. Proximity Effects on the Charge Density Wave Order and Superconductivity in Single-Layer NbSe 2. ACS NANO 2021; 15:19430-19438. [PMID: 34846856 PMCID: PMC8717633 DOI: 10.1021/acsnano.1c06012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 11/05/2021] [Indexed: 06/10/2023]
Abstract
Collective electronic states such as the charge density wave (CDW) order and superconductivity (SC) respond sensitively to external perturbations. Such sensitivity is dramatically enhanced in two dimensions (2D), where 2D materials hosting such electronic states are largely exposed to the environment. In this regard, the ineludible presence of supporting substrates triggers various proximity effects on 2D materials that may ultimately compromise the stability and properties of the electronic ground state. In this work, we investigate the impact of proximity effects on the CDW and superconducting states in single-layer (SL) NbSe2 on four substrates of diverse nature, namely, bilayer graphene (BLG), SL-boron nitride (h-BN), Au(111), and bulk WSe2. By combining low-temperature (340 mK) scanning tunneling microscopy/spectroscopy and angle-resolved photoemission spectroscopy, we compare the electronic structure of this prototypical 2D superconductor on each substrate. We find that, even when the electronic band structure of SL-NbSe2 remains largely unaffected by the substrate except when placed on Au(111), where a charge transfer occurs, both the CDW and SC show disparate behaviors. On the insulating h-BN/Ir(111) substrate and the metallic BLG/SiC(0001) substrate, both the 3 × 3 CDW and superconducting phases persist in SL-NbSe2 with very similar properties, which reveals the negligible impact of graphene on these electronic phases. In contrast, these collective electronic phases are severely weakened and even absent on the bulk insulating WSe2 substrate and the metallic single-crystal Au(111) substrate. Our results provide valuable insights into the fragile stability of such electronic ground states in 2D materials.
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Affiliation(s)
- Paul Dreher
- Donostia
International Physics Center (DIPC), Paseo Manuel de Lardizábal 4, 20018 San Sebastián, Spain
| | - Wen Wan
- Donostia
International Physics Center (DIPC), Paseo Manuel de Lardizábal 4, 20018 San Sebastián, Spain
| | - Alla Chikina
- Department
of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Marco Bianchi
- Department
of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Haojie Guo
- Departamento
de Física de la Materia Condensada, Universidad Autonoma de Madrid, Madrid E-28049, Spain
| | - Rishav Harsh
- Donostia
International Physics Center (DIPC), Paseo Manuel de Lardizábal 4, 20018 San Sebastián, Spain
| | - Samuel Mañas-Valero
- Instituto
de Ciencia Molecular (ICMol), Universitat
de València, c/
Catedrático José Beltrán 2, 46980 Paterna, Spain
| | - Eugenio Coronado
- Instituto
de Ciencia Molecular (ICMol), Universitat
de València, c/
Catedrático José Beltrán 2, 46980 Paterna, Spain
| | - Antonio J. Martínez-Galera
- Departamento
de Física de la Materia Condensada, Universidad Autonoma de Madrid, Madrid E-28049, Spain
- Insitituto
Nicolás Cabrera, Universidad Autnoma
de Madrid, Madrid E-28049, Spain
| | - Philip Hofmann
- Department
of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Jill A. Miwa
- Department
of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Miguel M. Ugeda
- Donostia
International Physics Center (DIPC), Paseo Manuel de Lardizábal 4, 20018 San Sebastián, Spain
- Centro
de Física de Materiales (CSIC-UPV-EHU), Paseo Manuel de Lardizábal 5, 20018 San Sebastián, Spain
- Ikerbasque,
Basque Foundation for Science, 48013 Bilbao, Spain
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24
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Saqib H, Rahman S, Zhao Y, Cazorla C, Errandonea D, Susilo R, Zhuang Y, Huang Y, Chen B, Dai N. Evolution of Structural and Electronic Properties of TiSe 2 under High Pressure. J Phys Chem Lett 2021; 12:9859-9867. [PMID: 34606285 DOI: 10.1021/acs.jpclett.1c02492] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
A pressure-induced structural phase transition and its intimate link with the superconducting transition was studied for the first time in TiSe2 up to 40 GPa at room temperature using X-ray diffraction, transport measurement, and first-principles calculations. We demonstrate the occurrence of a first-order structural phase transition at 4 GPa from the standard trigonal structure (S.G.P3̅m1) to another trigonal structure (S-G-P3̅c1). Additionally, at 16 GPa, the P3̅c1 phase spontaneously transforms into a monoclinic C2/m phase, and above 24 GPa, the C2/m phase returns to the initial P3̅m1 phase. Electrical transport results show that metallization occurs above 6 GPa. The charge density wave observed at ambient pressure is suppressed upon compression up to 2 GPa with the emergence of superconductivity at 2.5 GPa, with a critical temperature (Tc) of 2 K. A structural transition accompanies the emergence of superconductivity that persists up to 4 GPa. The results demonstrate that the pressure-induced phase transitions explored by the experiments along with the theoretical predictions may open the door to a new path for searching and controlling the phase diagrams of transition metal dichalcogenides.
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Affiliation(s)
- H Saqib
- Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China
- Shanghai Institute of Technical Physics, Chinese Academy of Science, Shanghai 201800, China
| | - S Rahman
- Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China
- School of Physics and Optoelectronic Engineering, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China
| | - Yongsheng Zhao
- Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China
| | - C Cazorla
- Departament de Física, Universitat Politècnica de Catalunya, Campus Nord B4-B5, Barcelona 08034, Spain
| | - D Errandonea
- Departamento de Física Aplicada-ICMUV, MALTA Consolider Team, Universidad de Valencia, Edificio de Investigación, C/Dr. Moliner 50, Burjassot, Valencia 46100, Spain
| | - Resta Susilo
- Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China
| | - Yukai Zhuang
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
| | - Yanwei Huang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
| | - Bin Chen
- Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China
| | - Ning Dai
- Shanghai Institute of Technical Physics, Chinese Academy of Science, Shanghai 201800, China
- School of Physics and Optoelectronic Engineering, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China
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25
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Nakata Y, Sugawara K, Chainani A, Oka H, Bao C, Zhou S, Chuang PY, Cheng CM, Kawakami T, Saruta Y, Fukumura T, Zhou S, Takahashi T, Sato T. Robust charge-density wave strengthened by electron correlations in monolayer 1T-TaSe 2 and 1T-NbSe 2. Nat Commun 2021; 12:5873. [PMID: 34620875 PMCID: PMC8497551 DOI: 10.1038/s41467-021-26105-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Accepted: 09/17/2021] [Indexed: 11/09/2022] Open
Abstract
Combination of low-dimensionality and electron correlation is vital for exotic quantum phenomena such as the Mott-insulating phase and high-temperature superconductivity. Transition-metal dichalcogenide (TMD) 1T-TaS2 has evoked great interest owing to its unique nonmagnetic Mott-insulator nature coupled with a charge-density-wave (CDW). To functionalize such a complex phase, it is essential to enhance the CDW-Mott transition temperature TCDW-Mott, whereas this was difficult for bulk TMDs with TCDW-Mott < 200 K. Here we report a strong-coupling 2D CDW-Mott phase with a transition temperature onset of ~530 K in monolayer 1T-TaSe2. Furthermore, the electron correlation derived lower Hubbard band survives under external perturbations such as carrier doping and photoexcitation, in contrast to the bulk counterpart. The enhanced Mott-Hubbard and CDW gaps for monolayer TaSe2 compared to NbSe2, originating in the lattice distortion assisted by strengthened correlations and disappearance of interlayer hopping, suggest stabilization of a likely nonmagnetic CDW-Mott insulator phase well above the room temperature. The present result lays the foundation for realizing monolayer CDW-Mott insulator based devices operating at room temperature.
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Affiliation(s)
- Yuki Nakata
- 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
- Center for Spintronics Research Network, Tohoku University, Sendai, 980-8577, Japan
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan
| | - Ashish Chainani
- National Synchrotron Radiation Research Center, Hshinchu, 30077, Taiwan ROC
| | - Hirofumi Oka
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan
| | - Changhua Bao
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, 100084, China
| | - Shaohua Zhou
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, 100084, China
| | - Pei-Yu Chuang
- National Synchrotron Radiation Research Center, Hshinchu, 30077, Taiwan ROC
| | - Cheng-Maw Cheng
- National Synchrotron Radiation Research Center, Hshinchu, 30077, Taiwan ROC
| | - Tappei Kawakami
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Yasuaki Saruta
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Tomoteru Fukumura
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Shuyun Zhou
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, 100084, China
- Frontier Science Center for Quantum Information, Beijing, 100084, China
| | - Takashi Takahashi
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
- Center for Spintronics Research Network, Tohoku University, Sendai, 980-8577, Japan
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan
| | - Takafumi Sato
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan.
- Center for Spintronics Research Network, Tohoku University, Sendai, 980-8577, Japan.
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan.
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26
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Li S, Zhang Z, Xu C, Liu Z, Chen X, Bian Q, Gedeon H, Shao Z, Liu L, Liu Z, Kang N, Cheng HM, Ren W, Pan M. Magnetic Doping Induced Superconductivity-to-Incommensurate Density Waves Transition in a 2D Ultrathin Cr-Doped Mo 2C Crystal. ACS NANO 2021; 15:14938-14946. [PMID: 34469117 DOI: 10.1021/acsnano.1c05133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In the vicinity of a competing electronic order, superconductivity emerges within a superconducting dome in the phase diagram, which has been demonstrated in unconventional superconductors and transition-metal dichalcogenides (TMDs), suggesting a scenario where fluctuations or a partial melting of a parent order are essential for inducing superconductivity. Here, we present a contrary example, the two-dimensional (2D) superconductivity in transition-metal carbide can be readily turned into charge density wave (CDW) phases via dilute magnetic doping. Low temperature scanning tunneling microscopy/spectroscopy (STM/STS), transport measurements, and density functional theory (DFT) calculations were employed to investigate Cr-doped superconducting Mo2C crystals in the 2D limit. With ultralow Cr doping (2.7 atom %), the superconductivity of Mo2C is heavily suppressed. Strikingly, an incommensurate density wave (IDW) and a related partially opened gap are observed at a temperature above the superconducting regime. The wave vector of IDW agrees well with the calculated Fermi surface nesting vectors. By further increasing the Cr doping level to 9.4 atom %, a stronger IDW with a smaller periodicity and a larger partial gap appear concurrently. The resistance anomaly implies the onset of the CDW phase. Spatial-resolved and temperature-dependent spectroscopy reveals that such CDW phases exist only in a nonsuperconducting regime and could form long-range orders uniformly. The results provide the understanding for the interplay between charge ordered states and superconductivity in 2D transition-metal carbide.
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Affiliation(s)
- Shaojian Li
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
| | - Zongyuan Zhang
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
- Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, P. R. China
| | - Chuan Xu
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, P. R. China
| | - Zhen Liu
- Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871, P. R. China
| | - Xiaorui Chen
- School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, China
| | - Qi Bian
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
| | - Habakubaho Gedeon
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
| | - Zhibin Shao
- School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, China
| | - Lijun Liu
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
| | - Zhibo Liu
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, P. R. China
| | - Ning Kang
- Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871, P. R. China
| | - Hui-Ming Cheng
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, P. R. China
- School of Materials Science and Engineering, University of Science and Technology of China, Shenyang 110016, P. R. China
- Shenzhen Geim Graphene Center, Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen 518055, P. R. China
| | - Wencai Ren
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, P. R. China
- School of Materials Science and Engineering, University of Science and Technology of China, Shenyang 110016, P. R. China
| | - Minghu Pan
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
- School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, China
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27
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Xu Z, Yang H, Song X, Chen Y, Yang H, Liu M, Huang Z, Zhang Q, Sun J, Liu L, Wang Y. Topical review: recent progress of charge density waves in 2D transition metal dichalcogenide-based heterojunctions and their applications. NANOTECHNOLOGY 2021; 32:492001. [PMID: 34450606 DOI: 10.1088/1361-6528/ac21ed] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 08/27/2021] [Indexed: 06/13/2023]
Abstract
Charge density wave (CDW) is an intriguing physical phenomenon especially found in two-dimensional (2D) layered systems such as transition-metal dichalcogenides (TMDs). The study of CDW is vital for understanding lattice modification, strongly correlated electronic behaviors, and other related physical properties. This paper gives a review of the recent studies on CDW emerging in 2D TMDs. First, a brief introduction and the main mechanisms of CDW are given. Second, the interplay between CDW patterns and the related unique electronic phenomena (superconductivity, spin, and Mottness) is elucidated. Then various manipulation methods such as doping, applying strain, local voltage pulse to induce the CDW change are discussed. Finally, examples of the potential application of devices based on CDW materials are given. We also discuss the current challenge and opportunities at the frontier in this research field.
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Affiliation(s)
- Ziqiang Xu
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, People's Republic of China
| | - Huixia Yang
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, People's Republic of China
| | - Xuan Song
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, People's Republic of China
| | - Yaoyao Chen
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, People's Republic of China
| | - Han Yang
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, People's Republic of China
| | - Meng Liu
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, People's Republic of China
| | - Zeping Huang
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, People's Republic of China
| | - Quanzhen Zhang
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, People's Republic of China
| | - Jiatao Sun
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, People's Republic of China
| | - Liwei Liu
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, People's Republic of China
| | - Yeliang Wang
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing, People's Republic of China
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28
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Coexistence of resistance oscillations and the anomalous metal phase in a lithium intercalated TiSe 2 superconductor. Nat Commun 2021; 12:5342. [PMID: 34504094 PMCID: PMC8429654 DOI: 10.1038/s41467-021-25671-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 08/22/2021] [Indexed: 11/24/2022] Open
Abstract
Superconductivity and charge density wave (CDW) appear in the phase diagram of a variety of materials including the high-Tc cuprate family and many transition metal dichalcogenides (TMDs). Their interplay may give rise to exotic quantum phenomena. Here, we show that superconducting arrays can spontaneously form in TiSe2–a TMD with coexisting superconductivity and CDW—after lithium ion intercalation. We induce a superconducting dome in the phase diagram of LixTiSe2 by using the ionic solid-state gating technique. Around optimal doping, we observe magnetoresistance oscillations, indicating the emergence of periodically arranged domains. In the same temperature, magnetic field and carrier density regime where the resistance oscillations occur, we observe signatures for the anomalous metal—a state with a resistance plateau across a wide temperature range below the superconducting transition. Our study not only sheds further insight into the mechanism for the periodic electronic structure, but also reveals the interplay between the anomalous metal and superconducting fluctuations. The interplay between superconductivity and charge density wave (CDW) gives rise to exotic quantum phenomena. Here, the authors observe magnetoresistance oscillations and an anomalous metal state due to the coexistence of superconductivity and CDW in lithium intercalated TiSe2.
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29
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Walmsley TS, Xu YQ. Enhanced photocurrent response speed in charge-density-wave phase of TiSe 2-metal junctions. NANOSCALE 2021; 13:11836-11843. [PMID: 34160523 DOI: 10.1039/d1nr01810h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Group IVB transition metal dichalcogenides (TMDCs) have attracted significant attention due to their predicted high charge carrier mobility, large sheet current density, and enhanced thermoelectric power. Here, we investigate the electrical and optoelectronic properties of few-layer titanium diselenide (TiSe2)-metal junctions through spatial-, wavelength-, temperature-, power- and temporal-dependent scanning photocurrent measurements. Strong photocurrent responses have been detected at TiSe2-metal junctions, which is likely attributed to both photovoltaic and photothermoelectric effects. A fast response time of 31 μs has been achieved, which is two orders of magnitude better than HfSe2 based devices. More importantly, our experimental results reveal a significant enhancement in the response speed upon cooling to the charge-density-wave (CDW) phase transition temperature (TCDW = 206 K), which may result from dramatic reduction in carrier scattering that occurs as a result of the switching between the normal and CDW phases of TiSe2. Additionally, the photoresponsivity at 145 K is up to an order of magnitude higher than that obtained at room temperature. These fundamental studies not only offer insight for the photocurrent generation mechanisms of group IVB TMDC materials, but also provide a route to engineering future temperature-dependent, two-dimensional, fast electronic and optoelectronic devices.
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Affiliation(s)
- Thayer S Walmsley
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235, USA.
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30
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Penev ES, Marzari N, Yakobson BI. Theoretical Prediction of Two-Dimensional Materials, Behavior, and Properties. ACS NANO 2021; 15:5959-5976. [PMID: 33823108 DOI: 10.1021/acsnano.0c10504] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Predictive modeling of two-dimensional (2D) materials is at the crossroad of two current rapidly growing interests: 2D materials per se, massively sought after and explored in experimental laboratories, and materials theoretical-computational models in general, flourishing on a fertile mix of condensed-matter physics and chemistry with advancing computational technology. Here the general methods and specific techniques of modeling are briefly overviewed, along with a somewhat philosophical assessment of what "prediction" is, followed by selected practical examples for 2D materials, from structures and properties, to device functionalities and synthetic routes for their making. We conclude with a brief sketch-outlook of future developments.
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Affiliation(s)
| | - Nicola Marzari
- Theory and Simulation of Materials (THEOS) and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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31
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Lin MK, He T, Hlevyack JA, Chen P, Mo SK, Chou MY, Chiang TC. Coherent Electronic Band Structure of TiTe 2/TiSe 2 Moiré Bilayer. ACS NANO 2021; 15:3359-3364. [PMID: 33570920 DOI: 10.1021/acsnano.0c10352] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A van der Waals bonded moiré bilayer formed by sequential growth of TiSe2 and TiTe2 monolayers exhibits emergent electronic structure as evidenced by angle-resolved photoemission band mapping. The two monolayers adopt the same lattice orientation but incommensurate lattice constants. Despite the lack of translational symmetry, sharp dispersive bands are observed. The dispersion relations appear distinct from those for the component monolayers alone. Theoretical calculations illustrate the formation of composite bands by coherent electronic coupling despite the weak interlayer bonding, which leads to band renormalization and energy shifts.
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Affiliation(s)
- Meng-Kai Lin
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Tao He
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - Joseph A Hlevyack
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Peng Chen
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, and Shanghai Center for Complex Physics, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Mei-Yin Chou
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - T-C Chiang
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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32
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Wang ZL, Chen G, Zhang X, Tang D. The first-principles and BTE investigation of phonon transport in 1T-TiSe2. Phys Chem Chem Phys 2021; 23:1627-1638. [DOI: 10.1039/d0cp06333a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Through the first-principles density functional theory and the phonon Boltzmann transport equation, we investigated the phonon transport characteristics inside 1T-TiSe2.
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Affiliation(s)
- Zhao-Liang Wang
- Department of Energy and Power Engineering
- China University of Petroleum
- Qingdao 266580
- China
| | - Guofu Chen
- Department of Energy and Power Engineering
- China University of Petroleum
- Qingdao 266580
- China
| | - Xiaoliang Zhang
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education
- School of Energy and Power Engineering
- Dalian University of Technology
- Dalian 116024
- China
| | - Dawei Tang
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education
- School of Energy and Power Engineering
- Dalian University of Technology
- Dalian 116024
- China
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33
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Mao Y, Ma X, Wu D, Lin C, Shan H, Wu X, Zhao J, Zhao A, Wang B. Interfacial Polarons in van der Waals Heterojunction of Monolayer SnSe 2 on SrTiO 3 (001). NANO LETTERS 2020; 20:8067-8073. [PMID: 33044080 DOI: 10.1021/acs.nanolett.0c02741] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Interfacial polarons have been demonstrated to play important roles in heterostructures containing polar substrates. However, most of polarons found so far are diffusive large polarons; the discovery and investigation of small polarons at interfaces are scarce. Herein, we report the emergence of interfacial polarons in monolayer SnSe2 epitaxially grown on Nb-doped SrTiO3 (STO) surface using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM). ARPES spectra taken on this heterointerface reveal a nearly flat in-gap band correlated with a significant charge modulation in real space as observed with STM. An interfacial polaronic model is proposed to ascribe this in-gap band to the formation of self-trapped small polarons induced by charge accumulation and electron-phonon coupling at the van der Waals interface of SnSe2 and STO. Such a mechanism to form interfacial polaron is expected to generally exist in similar van der Waals heterojunctions consisting of layered 2D materials and polar substrates.
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Affiliation(s)
- Yahui Mao
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xiaochuan Ma
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Daoxiong Wu
- CAS Key Laboratory of Materials for Energy Conservation, CAS Center for Excellence in Nanoscience, and Department of Material Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Chen Lin
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Huan Shan
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xiaojun Wu
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Key Laboratory of Materials for Energy Conservation, CAS Center for Excellence in Nanoscience, and Department of Material Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Jin Zhao
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- ICQD and CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Aidi Zhao
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Bing Wang
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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Lin MK, Hlevyack JA, Chen P, Liu RY, Mo SK, Chiang TC. Charge Instability in Single-Layer TiTe_{2} Mediated by van der Waals Bonding to Substrates. PHYSICAL REVIEW LETTERS 2020; 125:176405. [PMID: 33156647 DOI: 10.1103/physrevlett.125.176405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 09/10/2020] [Indexed: 06/11/2023]
Abstract
Single layers of transition metal dichalcogenides are of interest for emergent properties; an often-neglected issue is substrate effects. Our experiments show that the charge density wave in a single-layer TiTe_{2} grown on PtTe_{2} films is strongly suppressed by increasing the PtTe_{2} substrate thickness. Given that the interfacial bonding remains of the weak incommensurate van der Waals type, the observed changes are correlated with a thickness-dependent metallicity transformation in the PtTe_{2} substrate. The results illustrate the crucial role of the substrate in single-layer physics.
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Affiliation(s)
- Meng-Kai Lin
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Joseph A Hlevyack
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Peng Chen
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science and Shanghai Center for Complex Physics, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Ro-Ya Liu
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Institute of Physics, Academia Sinica, Taipei 10617, Taiwan
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - T-C Chiang
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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35
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Bianco R, Monacelli L, Calandra M, Mauri F, Errea I. Weak Dimensionality Dependence and Dominant Role of Ionic Fluctuations in the Charge-Density-Wave Transition of NbSe_{2}. PHYSICAL REVIEW LETTERS 2020; 125:106101. [PMID: 32955304 DOI: 10.1103/physrevlett.125.106101] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 07/30/2020] [Indexed: 06/11/2023]
Abstract
Contradictory experiments have been reported about the dimensionality effect on the charge-density-wave transition in 2H NbSe_{2}. While scanning tunneling experiments on single layers grown by molecular beam epitaxy measure a charge-density-wave transition temperature in the monolayer similar to the bulk, around 33 K, Raman experiments on exfoliated samples observe a large enhancement of the transition temperature up to 145 K. By employing a nonperturbative approach to deal with anharmonicity, we calculate from first principles the temperature dependence of the phonon spectra both for bulk and monolayer. In both cases, the charge-density-wave transition temperature is estimated as the temperature at which the phonon energy of the mode driving the structural instability vanishes. The obtained transition temperature in the bulk is around 59 K, in rather good agreement with experiments, and it is just slightly increased in the single-layer limit to 73 K, showing the weak dependence of the transition on dimensionality. Environmental factors could motivate the disagreement between the transition temperatures reported by experiments. Our analysis also demonstrates the predominance of ionic fluctuations over electronic ones in the melting of the charge-density-wave order.
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Affiliation(s)
- Raffaello Bianco
- Centro de Física de Materiales (CSIC-UPV/EHU), Manuel de Lardizabal pasealekua 5, 20018 Donostia/San Sebastián, Spain
| | - Lorenzo Monacelli
- Dipartimento di Fisica, Università di Roma Sapienza, Piazzale Aldo Moro 5, I-00185 Roma, Italy
- Graphene Labs, Fondazione Istituto Italiano di Tecnologia, Via Morego, I-16163 Genova, Italy
| | - Matteo Calandra
- Graphene Labs, Fondazione Istituto Italiano di Tecnologia, Via Morego, I-16163 Genova, Italy
- Dipartimento di Fisica, Università di Trento, Via Sommarive 14, 38123 Povo, Italy
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252 Paris, France
| | - Francesco Mauri
- Dipartimento di Fisica, Università di Roma Sapienza, Piazzale Aldo Moro 5, I-00185 Roma, Italy
- Graphene Labs, Fondazione Istituto Italiano di Tecnologia, Via Morego, I-16163 Genova, Italy
| | - Ion Errea
- Centro de Física de Materiales (CSIC-UPV/EHU), Manuel de Lardizabal pasealekua 5, 20018 Donostia/San Sebastián, Spain
- Fisika Aplikatua 1 Saila, Gipuzkoako Ingeniaritza Eskola, University of the Basque Country (UPV/EHU), Europa Plaza 1, 20018 Donostia/San Sebastián, Spain
- Donostia International Physics Center (DIPC), Manuel Lardizabal pasealekua 4, 20018 Donostia/San Sebastián, Spain
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36
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Kabiraj A, Mahapatra S. Machine-Intelligence-Driven High-Throughput Prediction of 2D Charge Density Wave Phases. J Phys Chem Lett 2020; 11:6291-6298. [PMID: 32698581 DOI: 10.1021/acs.jpclett.0c01846] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Charge density wave (CDW) materials are an important subclass of two-dimensional materials exhibiting significant resistivity switching with the application of external energy. However, the scarcity of such materials impedes their practical applications in nanoelectronics. Here we combine a first-principles-based structure-searching technique and unsupervised machine learning to develop a fully automated high-throughput computational framework, which identifies CDW phases from a unit cell with inherited Kohn anomaly. The proposed methodology not only rediscovers the known CDW phases but also predicts a host of easily exfoliable CDW materials (30 materials and 114 phases) along with associated electronic structures. Among many promising candidates, we pay special attention to ZrTiSe4 and conduct a comprehensive analysis to gain insight into the Fermi surface nesting, which causes significant semiconducting gap opening in its CDW phase. Our findings could provide useful guidelines for experimentalists.
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Affiliation(s)
- Arnab Kabiraj
- Nano-Scale Device Research Laboratory, Department of Electronic Systems Engineering, Indian Institute of Science (IISc) Bangalore, Bangalore - 560012, India
| | - Santanu Mahapatra
- Nano-Scale Device Research Laboratory, Department of Electronic Systems Engineering, Indian Institute of Science (IISc) Bangalore, Bangalore - 560012, India
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37
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Choi BK, Ulstrup S, Gunasekera SM, Kim J, Lim SY, Moreschini L, Oh JS, Chun SH, Jozwiak C, Bostwick A, Rotenberg E, Cheong H, Lyo IW, Mucha-Kruczynski M, Chang YJ. Visualizing Orbital Content of Electronic Bands in Anisotropic 2D Semiconducting ReSe 2. ACS NANO 2020; 14:7880-7891. [PMID: 32463224 DOI: 10.1021/acsnano.0c01054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Many properties of layered materials change as they are thinned from their bulk forms down to single layers, with examples including indirect-to-direct band gap transition in 2H semiconducting transition metal dichalcogenides as well as thickness-dependent changes in the valence band structure in post-transition-metal monochalcogenides and black phosphorus. Here, we use angle-resolved photoemission spectroscopy to study the electronic band structure of monolayer ReSe2, a semiconductor with a distorted 1T structure and in-plane anisotropy. By changing the polarization of incoming photons, we demonstrate that for ReSe2, in contrast to the 2H materials, the out-of-plane transition metal dz2 and chalcogen pz orbitals do not contribute significantly to the top of the valence band, which explains the reported weak changes in the electronic structure of this compound as a function of layer number. We estimate a band gap of 1.7 eV in pristine ReSe2 using scanning tunneling spectroscopy and explore the implications on the gap following surface doping with potassium. A lower bound of 1.4 eV is estimated for the gap in the fully doped case, suggesting that doping-dependent many-body effects significantly affect the electronic properties of ReSe2. Our results, supported by density functional theory calculations, provide insight into the mechanisms behind polarization-dependent optical properties of rhenium dichalcogenides and highlight their place among two-dimensional crystals.
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Affiliation(s)
- Byoung Ki Choi
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
| | - Søren Ulstrup
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
- Advanced Light Source (ALS), E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Surani M Gunasekera
- Centre for Nanoscience and Nanotechnology and Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - Jiho Kim
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
| | - Soo Yeon Lim
- Department of Physics, Sogang University, Seoul 04107, Republic of Korea
| | - Luca Moreschini
- Advanced Light Source (ALS), E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Ji Seop Oh
- Advanced Light Source (ALS), E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
| | - Seung-Hyun Chun
- Department of Physics, Sejong University, Seoul 05006, Republic of Korea
| | - Chris Jozwiak
- Advanced Light Source (ALS), E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Aaron Bostwick
- Advanced Light Source (ALS), E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Eli Rotenberg
- Advanced Light Source (ALS), E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Hyeonsik Cheong
- Department of Physics, Sogang University, Seoul 04107, Republic of Korea
| | - In-Whan Lyo
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
| | - Marcin Mucha-Kruczynski
- Centre for Nanoscience and Nanotechnology and Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - Young Jun Chang
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
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38
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Hu Q, Xu S, Guo X, Liu H, Chen Z, Wang B, Ang R. Superconductivity related to the suppression of exciton formation in 1T-TiSe 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:425602. [PMID: 32720648 DOI: 10.1088/1361-648x/aba1ab] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 07/01/2020] [Indexed: 06/11/2023]
Abstract
In strongly correlated electron system, the impact of elementary substitution or intercalation plays a crucial role in determining electronic ground state among various macroscopic quantum phases such as charge order and superconductivity. Here, we report that simultaneous Cu intercalation and Ta substitution at Ti site in 1T-CuxTi0.8Ta0.2Se2induce an intrinsic electronic phase diagram, characterized by an inherent superconducting transition in thexregion of 0 ⩽x⩽ 0.12, with a maximum superconducting transition temperatureTcof 2.5 K forx= 0.04, in contrast to the non-superconducting sample 1T-Cu0.04TiSe2. The increased density of free charge carriers screen the Coulomb interaction between electron-hole pairs effectively, promoting the occurrence of superconductivity favourably. Present results suggest that the Cu intercalation and the Ta substitution-induced suppression of the exciton condensation boost the superconductivity, shedding new light on the fundamental physics of the interplay between superconductivity, charge order, and electron correlation.
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Affiliation(s)
- Qing Hu
- Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, People's Republic of China
| | - Shuxiang Xu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Xuming Guo
- Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, People's Republic of China
| | - Hangtian Liu
- Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, People's Republic of China
| | - Zhiyu Chen
- Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, People's Republic of China
| | - Bosen Wang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
| | - Ran Ang
- Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, People's Republic of China
- Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610065, People's Republic of China
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39
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Zhou JS, Monacelli L, Bianco R, Errea I, Mauri F, Calandra M. Anharmonicity and Doping Melt the Charge Density Wave in Single-Layer TiSe 2. NANO LETTERS 2020; 20:4809-4815. [PMID: 32496779 DOI: 10.1021/acs.nanolett.0c00597] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Low-dimensional systems with a vanishing band gap and a large electron-hole interaction have been proposed to be unstable toward exciton formation. As the exciton binding energy increases in low dimension, conventional wisdom suggests that excitonic insulators should be more stable in 2D than in 3D. Here we study the effects of the electron-hole interaction and anharmonicity in single-layer TiSe2. We find that, contrary to the bulk case and to the generally accepted picture, in single-layer TiSe2, the electron-hole exchange interaction is much smaller in 2D than in 3D and it has weak effects on phonon spectra. By calculating anharmonic phonon spectra within the stochastic self-consistent harmonic approximation, we obtain TCDW ≈ 440 K for an isolated and undoped single layer and TCDW ≈ 364 K for an electron-doping n = 4.6 × 1013 cm-2, close to the experimental result of 200-280 K on supported samples. Our work demonstrates that anharmonicity and doping melt the charge density wave in single-layer TiSe2.
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Affiliation(s)
- Jianqiang Sky Zhou
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252, Paris, France
| | - Lorenzo Monacelli
- Dipartimento di Fisica, Università di Roma Sapienza, Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Raffaello Bianco
- Centro de Física de Materiales (CSIC-UPV/EHU), Manuel de Lardizabal pasealekua 5, 20018 Donostia-San Sebastián, Basque Country, Spain
| | - Ion Errea
- Fisika Aplikatua 1 Saila, Gipuzkoako Ingeniaritza Eskola, University of the Basque Country (UPV/EHU), Europa Plaza 1, 20018 Donostia-San Sebastián, Basque Country, Spain
- Centro de Física de Materiales (CSIC-UPV/EHU), Manuel de Lardizabal pasealekua 5, 20018 Donostia-San Sebastián, Basque Country, Spain
- Donostia International Physics Center (DIPC), Manuel de Lardizabal pasealekua 4, 20018 Donostia-San Sebastián, Basque Country, Spain
| | - Francesco Mauri
- Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 5, I-00185 Roma, Italy
- Graphene Laboratories, Fondazione Istituto Italiano di Tecnologia, Via Morego, I-16163 Genova, Italy
| | - Matteo Calandra
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252, Paris, France
- Department of Physics, University of Trento, Via Sommarive 14, 38123 Povo, Italy
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40
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Chen K, Deng J, Shi Q, Ding X, Sun J, Yang S, Liu JZ. Charge doping induced reversible multistep structural phase transitions and electromechanical actuation in two-dimensional 1T'-MoS 2. NANOSCALE 2020; 12:12541-12550. [PMID: 32500127 DOI: 10.1039/d0nr02049d] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The 1T' phase of transition metal dichalcogenides (TMDs) is a low symmetry charge density wave (CDW) phase, which can be viewed as a periodically distorted structure (Peierls distortion) of the high symmetry 1T phase. In this paper, using density functional theory (DFT) calculations, we report that the positive charge (hole) injection is an effective method to modulate the Peierls distortion of MoS2 1T' for a new CDW phase and superior electromechanical properties. A new stable CDW phase is discovered at a hole doping level of 0.10 h+ per atom, named 1T't. Hole charging and discharging can induce a reversible phase transition of MoS2 among the three phases, 1T, 1T' and 1T't. Such a reversible phase transition leads to superior electromechanical properties including a strain output as high as -5.8% with a small hysteresis loop, multi-step super-elasticity, and multi-shape memory effect, which are valuable in active electromechanical device designs at the nanoscale. In-depth analysis of the change of the electronic structure under hole doping was performed to understand the new CDW phase and the observed phase transition. Using charge doping to modulate the Peierls distortion in two-dimensional materials can serve as a general concept for nano-active material designs.
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Affiliation(s)
- Kaiyun Chen
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Junkai Deng
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Qian Shi
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Xiangdong Ding
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Jun Sun
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Sen Yang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Jefferson Zhe Liu
- Department of Mechanical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia.
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41
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Patterns and driving forces of dimensionality-dependent charge density waves in 2H-type transition metal dichalcogenides. Nat Commun 2020; 11:2406. [PMID: 32415071 PMCID: PMC7229047 DOI: 10.1038/s41467-020-15715-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 03/26/2020] [Indexed: 12/02/2022] Open
Abstract
Charge density wave (CDW) is a startling quantum phenomenon, distorting a metallic lattice into an insulating state with a periodically modulated charge distribution. Astonishingly, such modulations appear in various patterns even within the same family of materials. Moreover, this phenomenon features a puzzling diversity in its dimensional evolution. Here, we propose a general framework, unifying distinct trends of CDW ordering in an isoelectronic group of materials, 2H-MX2 (M = Nb, Ta and X = S, Se). We show that while NbSe2 exhibits a strongly enhanced CDW order in two dimensions, TaSe2 and TaS2 behave oppositely, with CDW being absent in NbS2 entirely. Such a disparity is demonstrated to arise from a competition of ionic charge transfer, electron-phonon coupling, and electron correlation. Despite its simplicity, our approach can, in principle, explain dimensional dependence of CDW in any material, thereby shedding new light on this intriguing quantum phenomenon and its underlying mechanisms. The dimensional dependence of charge density wave (CDW) in two-dimensional dichalcogenides remains puzzled. Here, Lin et al. study trends of CDW ordering in an isoelectronic group of materials 2H-MX2 and provide a unified understanding involving several microscopic factors.
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42
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Li Z, Song Y, Tang S. Quantum spin Hall state in monolayer 1T '-TMDCs. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:333001. [PMID: 32244235 DOI: 10.1088/1361-648x/ab8660] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 04/03/2020] [Indexed: 06/11/2023]
Abstract
Although the 1T'phase is rare in the transition metal dichalcogenides (TMDCs) family, it has attracted rapid growing research interest due to the coexistence of superconductivity, unsaturated magneto-resistance, topological phases etc. Among them, the quantum spin Hall (QSH) state in monolayer 1T'-TMDCs is especially interesting because of its unique van der Waals crystal structure, bringing advantages in the fundamental research and application. For example, the van der Waals two-dimensional (2D) layer is vital in building novel functional vertical heterostructure. The monolayer 1T'-TMDCs has become one of the widely studied QSH insulator. In this review, we review the recent progress in fabrications of monolayer 1T'-TMDCs and evidence that establishes it as QSH insulator.
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Affiliation(s)
- Zhuojun Li
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
- CAS Center for Excellence in Superconducting Electronics (CENSE), Shanghai 200050, People's Republic of China
| | - Yekai Song
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
- CAS Center for Excellence in Superconducting Electronics (CENSE), Shanghai 200050, People's Republic of China
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 200031, People's Republic of China
| | - Shujie Tang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China
- CAS Center for Excellence in Superconducting Electronics (CENSE), Shanghai 200050, People's Republic of China
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43
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Liu X, Ding Z, Liu J, Hu W, Yang J. Two-dimensional Ca 4N 2 as a one-dimensional electride [Ca 4N 2] 2+·2e - with ultrahigh conductance. NANOSCALE 2020; 12:5578-5586. [PMID: 32096537 DOI: 10.1039/c9nr10765g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Electrides possess high electrical conductance and reactivity and are promising for novel applications in electronics and catalysis. Here, we predict a new thermodynamically and kinetically stable two-dimensional (2D) Ca4N2 using first-principles density functional theory (DFT) calculations. 2D Ca4N2 can serve as a one-dimensional (1D) electride [Ca4N2]2+·2e- with anionic electrons confined in the surface channels. In particular, we demonstrate that 2D Ca4N2 possesses high Fermi velocity (0.42 × 106 m s-1), electron effective Fermi mass (∼1me), ultrahigh charge density (1.14 × 1015 cm-2), and high carrier mobility (215 and 5.29 × 106 cm2 V-1 s-1 at a room temperature of 300 K and a low temperature of 2 K), resulting in ultrahigh conductance up to 0.039 and 966 S respectively for 300 and 2 K, compared to existing 2D materials and the best conductors (Cu and Ag). Furthermore, the first finding of 1D anionic electron behaviour on the surface of 2D materials can be used to stimulate the design of new kinds of electrides for exploring the physics of 1D and quasi-1D systems.
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Affiliation(s)
- Xiaofeng Liu
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Chemical Physics, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
| | - Zijing Ding
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Chemical Physics, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
| | - Jie Liu
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Chemical Physics, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
| | - Wei Hu
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Chemical Physics, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
| | - Jinlong Yang
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Chemical Physics, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
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Wang X, Song Z, Wen W, Liu H, Wu J, Dang C, Hossain M, Iqbal MA, Xie L. Potential 2D Materials with Phase Transitions: Structure, Synthesis, and Device Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1804682. [PMID: 30393917 DOI: 10.1002/adma.201804682] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Revised: 09/04/2018] [Indexed: 06/08/2023]
Abstract
Layered materials with phase transitions, such as charge density wave (CDW) and magnetic and dipole ordering, have potential to be exfoliated into monolayers and few-layers and then become a large and important subfamily of two-dimensional (2D) materials. Benefitting from enriched physical properties from the collective interactions, long-range ordering, and related phase transitions, as well as the atomic thickness yet having nondangling bonds on the surface, 2D phase-transition materials have vast potential for use in new-concept and functional devices. Here, potential 2D phase-transition materials with CDWs and magnetic and dipole ordering, including transition metal dichalcogenides, transition metal halides, metal thio/selenophosphates, chromium silicon/germanium tellurides, and more, are introduced. The structures and experimental phase-transition properties are summarized for the bulk materials and some of the obtained monolayers. In addition, recent experimental progress on the synthesis and measurement of monolayers, such as 1T-TaS2 , CrI3 , and Cr2 Ge2 Te6 , is reviewed.
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Affiliation(s)
- Xinsheng Wang
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Zhigang Song
- Department of Engineering, University of Cambridge, JJ Thomson Avenue, CB3 0FA, Cambridge, UK
| | - Wen Wen
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Haining Liu
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Juanxia Wu
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Chunhe Dang
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Mongur Hossain
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Muhammad Ahsan Iqbal
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Liming Xie
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
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45
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Coelho PM, Lasek K, Nguyen Cong K, Li J, Niu W, Liu W, Oleynik II, Batzill M. Monolayer Modification of VTe 2 and Its Charge Density Wave. J Phys Chem Lett 2019; 10:4987-4993. [PMID: 31411022 DOI: 10.1021/acs.jpclett.9b01949] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Interlayer interactions in layered transition metal dichalcogenides are known to be important for describing their electronic properties. Here, we demonstrate that the absence of interlayer coupling in monolayer VTe2 also causes their structural modification from a distorted 1T' structure in bulk and multilayer samples to a hexagonal 1T structure in the monolayer. X-ray photoemission spectroscopy indicates that this structural transition is associated with electron transfer from the vanadium d bands to the tellurium atoms for the monolayer. This charge transfer may reduce the in-plane d orbital hybridization and thus favor the undistorted 1T structure. Phonon-dispersion calculations show that, in contrast to the 1T' structure, the 1T structure exhibits imaginary phonon modes that lead to a charge density wave (CDW) instability, which is also observed by low-temperature scanning tunneling microscopy as a 4 × 4 periodic lattice distortion. Thus, this work demonstrates a novel CDW material, whose properties are tuned by interlayer interactions.
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Affiliation(s)
- Paula Mariel Coelho
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
| | - Kinga Lasek
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
| | - Kien Nguyen Cong
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
| | - Jingfeng Li
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
| | - Wei Niu
- Department of Electronic Engineering, Royal Holloway University of London, Egham TW20 0EX, U.K
- New Energy Technology Engineering Laboratory of Jiangsu Provence and School of Science, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
| | - Wenqing Liu
- Department of Electronic Engineering, Royal Holloway University of London, Egham TW20 0EX, U.K
| | - Ivan I Oleynik
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
| | - Matthias Batzill
- Department of Physics, University of South Florida, Tampa, Florida 33620, United States
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Shao Z, Fu ZG, Li S, Cao Y, Bian Q, Sun H, Zhang Z, Gedeon H, Zhang X, Liu L, Cheng Z, Zheng F, Zhang P, Pan M. Strongly Compressed Few-Layered SnSe 2 Films Grown on a SrTiO 3 Substrate: The Coexistence of Charge Ordering and Enhanced Interfacial Superconductivity. NANO LETTERS 2019; 19:5304-5312. [PMID: 31287705 DOI: 10.1021/acs.nanolett.9b01766] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
High pressure has been demonstrated to be a powerful approach of producing novel condensed-matter states, particularly in tuning the superconducting transition temperature (Tc) of the superconductivity in a clean fashion without involving the complexity of chemical doping. However, the challenge of high-pressure experiment hinders further in-depth research for underlying mechanisms. Here, we have successfully synthesized continuous layer-controllable SnSe2 films on SrTiO3 substrate using molecular beam epitaxy. By means of scanning tunneling microscopy/spectroscopy (STM/S) and Raman spectroscopy, we found that the strong compressive strain is intrinsically built in few-layers films, with a largest equivalent pressure up to 23 GPa in the monolayer. Upon this, unusual 2 × 2 charge ordering is induced at the occupied states in the monolayer, accompanied by prominent decrease in the density of states (DOS) near the Fermi energy (EF), resembling the gap states of CDW reported in transition metal dichalcogenide (TMD) materials. Subsequently, the coexistence of charge ordering and the interfacial superconductivity is observed in bilayer films as a result of releasing the compressive strain. In conjunction with spatially resolved spectroscopic study and first-principles calculation, we find that the enhanced interfacial superconductivity with an estimated Tc of 8.3 K is observed only in the 1 × 1 region. Such superconductivity can be ascribed to a combined effect of interfacial charge transfer and compressive strain, which leads to a considerable downshift of the conduction band minimum and an increase in the DOS at EF. Our results provide an attractive platform for further in-depth investigation of compression-induced charge ordering (monolayer) and the interplay between charge ordering and superconductivity (bilayer). Meanwhile, it has opened up a pathway to prepare strongly compressed two-dimensional materials by growing onto a SrTiO3 substrate, which is promising to induce superconductivity with a higher Tc.
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Affiliation(s)
- Zhibin Shao
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Zhen-Guo Fu
- Institute of Applied Physics and Computational Mathematics , Beijing 100088 , China
| | - Shaojian Li
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Yan Cao
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Qi Bian
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Haigen Sun
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Zongyuan Zhang
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Habakubaho Gedeon
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Xin Zhang
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Lijun Liu
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Zhengwang Cheng
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Fawei Zheng
- Institute of Applied Physics and Computational Mathematics , Beijing 100088 , China
| | - Ping Zhang
- Institute of Applied Physics and Computational Mathematics , Beijing 100088 , China
| | - Minghu Pan
- School of Physics , Huazhong University of Science and Technology , Wuhan 430074 , China
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Lin H, Zhu Q, Shu D, Lin D, Xu J, Huang X, Shi W, Xi X, Wang J, Gao L. Growth of environmentally stable transition metal selenide films. NATURE MATERIALS 2019; 18:602-607. [PMID: 30858568 DOI: 10.1038/s41563-019-0321-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 02/11/2019] [Indexed: 06/09/2023]
Abstract
Two-dimensional transition metal selenides (TMSs) possess fascinating physical properties. However, many as-prepared TMSs are environmentally unstable and limited in sample size, which greatly hinder their wide applications in high-performance electrical devices. Here we develop a general two-step vapour deposition method and successfully grow different TMS films with controllable thickness, wafer size and high quality. The superconductivity of the grown NbSe2 film is comparable with sheets exfoliated from bulk materials, and can maintain stability after a variety of harsh treatments, which are ascribed to the absence of oxygen during the whole growth process. Such environmental stability can greatly simplify the fabrication procedure for device applications, and should be of both fundamental and technological significance in developing TMS-based devices.
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Affiliation(s)
- Huihui Lin
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Qi Zhu
- Center of Electron Microscopy and State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, China
| | - Dajun Shu
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Dongjing Lin
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Jie Xu
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Xianlei Huang
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Wei Shi
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Xiaoxiang Xi
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Jiangwei Wang
- Center of Electron Microscopy and State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, China.
| | - Libo Gao
- National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.
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48
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Chen P, Chen YT, Liu RY, Chen HD, Lin D, Fedorov AV, Chiang TC. Atomic-Scale Chemical Conversion of Single-Layer Transition Metal Dichalcogenides. ACS NANO 2019; 13:5611-5615. [PMID: 30987421 DOI: 10.1021/acsnano.9b00756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Chemical conversion by atomic substitution offers a powerful route toward the creation of unusual structures and functionalities. Here, we demonstrate the progressive transformation of single-layer TiTe2 into TiSe2 by reaction with a Se flux in vacuum. Angle-resolved photoemission spectroscopy and scanning tunneling microscopy reveal intriguing reaction patterns involving TiSe2 island ingrowth starting from the TiTe2 island edges, while the band structure and core level signatures of TiSe2 grow in intensity at the expense of those corresponding to TiTe2. Lattice mismatch between TiTe2 and TiSe2 results in misfit holes and lattice distortions over a distance behind a seamless fingerlike reaction front. The regions of TiSe2 and TiTe2 are distinguished by a height difference and a charge density wave (CDW) at different transition temperatures. The method of in situ chemical conversion offers opportunities for atomic-scale engineering of layered transition metal dichalcogenides that host useful properties arising from CDW, Dirac, Weyl, superconducting, spin-valley, and magnetic structures.
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Affiliation(s)
- Peng Chen
- Department of Physics , University of Illinois at Urbana-Champaign , 1110 West Green Street , Urbana , Illinois 61801-3080 , United States
- Frederick Seitz Materials Research Laboratory , University of Illinois at Urbana-Champaign , 104 South Goodwin Avenue , Urbana , Illinois 61801-2902 , United States
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Yun-Ting Chen
- Department of Physics , National Tsing Hua University , Hsinchu 30013 , Taiwan
| | - Ro-Ya Liu
- Department of Physics , University of Illinois at Urbana-Champaign , 1110 West Green Street , Urbana , Illinois 61801-3080 , United States
- Frederick Seitz Materials Research Laboratory , University of Illinois at Urbana-Champaign , 104 South Goodwin Avenue , Urbana , Illinois 61801-2902 , United States
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
- Institute of Physics , Academia Sinica , Taipei 11529 , Taiwan
| | - Han-De Chen
- Department of Physics , National Tsing Hua University , Hsinchu 30013 , Taiwan
| | - Dengsung Lin
- Department of Physics , National Tsing Hua University , Hsinchu 30013 , Taiwan
| | - Alexei V Fedorov
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Tai-Chang Chiang
- Department of Physics , University of Illinois at Urbana-Champaign , 1110 West Green Street , Urbana , Illinois 61801-3080 , United States
- Frederick Seitz Materials Research Laboratory , University of Illinois at Urbana-Champaign , 104 South Goodwin Avenue , Urbana , Illinois 61801-2902 , United States
- Department of Physics , National Taiwan University , Taipei 10617 , Taiwan
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49
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Zhou Y, Pondick JV, Silva JL, Woods JM, Hynek DJ, Matthews G, Shen X, Feng Q, Liu W, Lu Z, Liang Z, Brena B, Cai Z, Wu M, Jiao L, Hu S, Wang H, Araujo CM, Cha JJ. Unveiling the Interfacial Effects for Enhanced Hydrogen Evolution Reaction on MoS 2 /WTe 2 Hybrid Structures. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1900078. [PMID: 30957970 DOI: 10.1002/smll.201900078] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Revised: 02/14/2019] [Indexed: 06/09/2023]
Abstract
Using the MoS2 -WTe2 heterostructure as a model system combined with electrochemical microreactors and density function theory calculations, it is shown that heterostructured contacts enhance the hydrogen evolution reaction (HER) activity of monolayer MoS2 . Two possible mechanisms are suggested to explain this enhancement: efficient charge injection through large-area heterojunctions between MoS2 and WTe2 and effective screening of mirror charges due to the semimetallic nature of WTe2 . The dielectric screening effect is proven minor, probed by measuring the HER activity of monolayer MoS2 on various support substrates with dielectric constants ranging from 4 to 300. Thus, the enhanced HER is attributed to the increased charge injection into MoS2 through large-area heterojunctions. Based on this understanding, a MoS2 /WTe2 hybrid catalyst is fabricated with an HER overpotential of -140 mV at 10 mA cm-2 , a Tafel slope of 40 mV dec-1 , and long stability. These results demonstrate the importance of interfacial design in transition metal dichalcogenide HER catalysts. The microreactor platform presents an unambiguous approach to probe interfacial effects in various electrocatalytic reactions.
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Affiliation(s)
- Yu Zhou
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, 06511, USA
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06525, USA
| | - Joshua V Pondick
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, 06511, USA
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06525, USA
| | - Jose Luis Silva
- Materials Theory Division, Department of Physics and Astronomy, Uppsala University, Uppsala, 75120, Sweden
| | - John M Woods
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, 06511, USA
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06525, USA
| | - David J Hynek
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, 06511, USA
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06525, USA
| | - Grace Matthews
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, 27695, USA
| | - Xin Shen
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06525, USA
- Department of Chemical and Environmental Engineering, Yale University, New Haven, CT, 06511, USA
| | - Qingliang Feng
- Shaanxi Key Laboratory of Optical Information Technology, School of Science, Northwestern Polytechnical University, Xi'an, 710072, P. R. China
| | - Wen Liu
- Department of Chemistry, Yale University, New Haven, CT, 06511, USA
| | - Zhixing Lu
- Department of Chemistry, Tsinghua University, Beijing, 10084, P. R. China
| | - Zhixiu Liang
- Department of Chemistry, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Barbara Brena
- Materials Theory Division, Department of Physics and Astronomy, Uppsala University, Uppsala, 75120, Sweden
| | - Zhao Cai
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06525, USA
- Department of Chemistry, Yale University, New Haven, CT, 06511, USA
| | - Min Wu
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06525, USA
- Department of Chemistry, Yale University, New Haven, CT, 06511, USA
| | - Liying Jiao
- Department of Chemistry, Tsinghua University, Beijing, 10084, P. R. China
| | - Shu Hu
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06525, USA
- Department of Chemical and Environmental Engineering, Yale University, New Haven, CT, 06511, USA
| | - Hailiang Wang
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06525, USA
- Department of Chemistry, Yale University, New Haven, CT, 06511, USA
| | - Carlos Moyses Araujo
- Materials Theory Division, Department of Physics and Astronomy, Uppsala University, Uppsala, 75120, Sweden
| | - Judy J Cha
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, 06511, USA
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06525, USA
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50
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Vega-Mayoral V, Tian R, Kelly AG, Griffin A, Harvey A, Borrelli M, Nisi K, Backes C, Coleman JN. Solvent exfoliation stabilizes TiS 2 nanosheets against oxidation, facilitating lithium storage applications. NANOSCALE 2019; 11:6206-6216. [PMID: 30874697 DOI: 10.1039/c8nr09446b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Titanium disulfide is a promising material for a range of applications, including lithium-ion battery (LIB) anodes. However, its application potential has been severely hindered by the tendency of exfoliated TiS2 to rapidly oxidize under ambient conditions. Herein, we confirm that, although layered TiS2 powder can be exfoliated by sonication in aqueous surfactant solutions, the resultant nanosheets oxidise almost completely within hours. However, we find that upon performing the exfoliation in the solvent cyclohexyl-pyrrolidone (CHP), the oxidation is almost completely suppressed. TiS2 nanosheets dispersed in CHP and stored at 4 °C in an open atmosphere for 90 days remained up to 95% intact. In addition, CHP-exfoliated nanosheets did not show any evidence of oxidation for at least 30 days after being transformed into dry films even when stored under ambient conditions. This stability, probably a result of a residual CHP coating, allows TiS2 nanosheets to be deployed in applications. To demonstrate this, we prepared lithium ion battery anodes from nano : nano composites of TiS2 nanosheets mixed with carbon nanotubes. These anodes displayed reversible capacities (920 mA h g-1) close to the theoretical value and showed good rate performance and cycling capability.
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