1
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Gao Y, Weston A, Enaldiev V, Li X, Wang W, Nunn JE, Soltero I, Castanon EG, Carl A, De Latour H, Summerfield A, Hamer M, Howarth J, Clark N, Wilson NR, Kretinin AV, Fal'ko VI, Gorbachev R. Tunnel junctions based on interfacial two dimensional ferroelectrics. Nat Commun 2024; 15:4449. [PMID: 38789446 PMCID: PMC11126694 DOI: 10.1038/s41467-024-48634-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 05/09/2024] [Indexed: 05/26/2024] Open
Abstract
Van der Waals heterostructures have opened new opportunities to develop atomically thin (opto)electronic devices with a wide range of functionalities. The recent focus on manipulating the interlayer twist angle has led to the observation of out-of-plane room temperature ferroelectricity in twisted rhombohedral bilayers of transition metal dichalcogenides. Here we explore the switching behaviour of sliding ferroelectricity using scanning probe microscopy domain mapping and tunnelling transport measurements. We observe well-pronounced ambipolar switching behaviour in ferroelectric tunnelling junctions with composite ferroelectric/non-polar insulator barriers and support our experimental results with complementary theoretical modelling. Furthermore, we show that the switching behaviour is strongly influenced by the underlying domain structure, allowing the fabrication of diverse ferroelectric tunnelling junction devices with various functionalities. We show that to observe the polarisation reversal, at least one partial dislocation must be present in the device area. This behaviour is drastically different from that of conventional ferroelectric materials, and its understanding is an important milestone for the future development of optoelectronic devices based on sliding ferroelectricity.
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Affiliation(s)
- Yunze Gao
- Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
- National Graphene Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Astrid Weston
- Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
- National Graphene Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Vladimir Enaldiev
- Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
- National Graphene Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Xiao Li
- Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
- National Graphene Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Wendong Wang
- Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
- National Graphene Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - James E Nunn
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
| | - Isaac Soltero
- Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
- National Graphene Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Eli G Castanon
- Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
- National Graphene Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Amy Carl
- Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
- National Graphene Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Hugo De Latour
- Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
- National Graphene Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Alex Summerfield
- Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
- National Graphene Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Matthew Hamer
- Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
- National Graphene Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - James Howarth
- Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
- National Graphene Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Nicholas Clark
- Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
- National Graphene Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Neil R Wilson
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
| | - Andrey V Kretinin
- Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
- National Graphene Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
- Department of Materials, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
| | - Vladimir I Fal'ko
- Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
- National Graphene Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
- Henry Royce Institute for Advanced Materials, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
| | - Roman Gorbachev
- Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
- National Graphene Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
- Henry Royce Institute for Advanced Materials, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
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2
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Sun X, Suriyage M, Khan AR, Gao M, Zhao J, Liu B, Hasan MM, Rahman S, Chen RS, Lam PK, Lu Y. Twisted van der Waals Quantum Materials: Fundamentals, Tunability, and Applications. Chem Rev 2024; 124:1992-2079. [PMID: 38335114 DOI: 10.1021/acs.chemrev.3c00627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2024]
Abstract
Twisted van der Waals (vdW) quantum materials have emerged as a rapidly developing field of two-dimensional (2D) semiconductors. These materials establish a new central research area and provide a promising platform for studying quantum phenomena and investigating the engineering of novel optoelectronic properties such as single photon emission, nonlinear optical response, magnon physics, and topological superconductivity. These captivating electronic and optical properties result from, and can be tailored by, the interlayer coupling using moiré patterns formed by vertically stacking atomic layers with controlled angle misorientation or lattice mismatch. Their outstanding properties and the high degree of tunability position them as compelling building blocks for both compact quantum-enabled devices and classical optoelectronics. This paper offers a comprehensive review of recent advancements in the understanding and manipulation of twisted van der Waals structures and presents a survey of the state-of-the-art research on moiré superlattices, encompassing interdisciplinary interests. It delves into fundamental theories, synthesis and fabrication, and visualization techniques, and the wide range of novel physical phenomena exhibited by these structures, with a focus on their potential for practical device integration in applications ranging from quantum information to biosensors, and including classical optoelectronics such as modulators, light emitting diodes, lasers, and photodetectors. It highlights the unique ability of moiré superlattices to connect multiple disciplines, covering chemistry, electronics, optics, photonics, magnetism, topological and quantum physics. This comprehensive review provides a valuable resource for researchers interested in moiré superlattices, shedding light on their fundamental characteristics and their potential for transformative applications in various fields.
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Affiliation(s)
- Xueqian Sun
- School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Manuka Suriyage
- School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Ahmed Raza Khan
- School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
- Department of Industrial and Manufacturing Engineering, University of Engineering and Technology (Rachna College Campus), Gujranwala, Lahore 54700, Pakistan
| | - Mingyuan Gao
- School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
- College of Engineering and Technology, Southwest University, Chongqing 400716, China
| | - Jie Zhao
- Department of Quantum Science & Technology, Research School of Physics, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
- Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Boqing Liu
- School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Md Mehedi Hasan
- School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Sharidya Rahman
- Department of Materials Science and Engineering, Monash University, Clayton, Victoria 3800, Australia
- ARC Centre of Excellence in Exciton Science, Monash University, Clayton, Victoria 3800, Australia
| | - Ruo-Si Chen
- School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Ping Koy Lam
- Department of Quantum Science & Technology, Research School of Physics, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Republic of Singapore
- Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Yuerui Lu
- School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
- Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
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3
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Yang Y, Morales MA, Zhang S. Metal-Insulator Transition in a Semiconductor Heterobilayer Model. PHYSICAL REVIEW LETTERS 2024; 132:076503. [PMID: 38427879 DOI: 10.1103/physrevlett.132.076503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 01/17/2024] [Indexed: 03/03/2024]
Abstract
Transition metal dichalcogenide superlattices provide an exciting new platform for exploring and understanding a variety of phases of matter. The moiré continuum Hamiltonian, of two-dimensional jellium in a modulating potential, provides a fundamental model for such systems. Accurate computations with this model are essential for interpreting experimental observations and making predictions for future explorations. In this work, we combine two complementary quantum Monte Carlo (QMC) methods, phaseless auxiliary field quantum Monte Carlo and fixed-phase diffusion Monte Carlo, to study the ground state of this Hamiltonian. We observe a metal-insulator transition between a paramagnet and a 120° Néel ordered state as the moiré potential depth and the interaction strength are varied. We find significant differences from existing results by Hartree-Fock and exact diagonalization studies. In addition, we benchmark density-functional theory, and suggest an optimal hybrid functional which best approximates our QMC results.
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Affiliation(s)
- Yubo Yang
- Center for Computational Quantum Physics, Flatiron Institute, New York, New York 10010, USA
| | - Miguel A Morales
- Center for Computational Quantum Physics, Flatiron Institute, New York, New York 10010, USA
| | - Shiwei Zhang
- Center for Computational Quantum Physics, Flatiron Institute, New York, New York 10010, USA
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4
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Jiao C, Pei S, Wu S, Wang Z, Xia J. Tuning and exploiting interlayer coupling in two-dimensional van der Waals heterostructures. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2023; 86:114503. [PMID: 37774692 DOI: 10.1088/1361-6633/acfe89] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Accepted: 09/29/2023] [Indexed: 10/01/2023]
Abstract
Two-dimensional (2D) layered materials can stack into new material systems, with van der Waals (vdW) interaction between the adjacent constituent layers. This stacking process of 2D atomic layers creates a new degree of freedom-interlayer interface between two adjacent layers-that can be independently studied and tuned from the intralayer degree of freedom. In such heterostructures (HSs), the physical properties are largely determined by the vdW interaction between the individual layers,i.e.interlayer coupling, which can be effectively tuned by a number of means. In this review, we summarize and discuss a number of such approaches, including stacking order, electric field, intercalation, and pressure, with both their experimental demonstrations and theoretical predictions. A comprehensive overview of the modulation on structural, optical, electrical, and magnetic properties by these four approaches are also presented. We conclude this review by discussing several prospective research directions in 2D HSs field, including fundamental physics study, property tuning techniques, and future applications.
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Affiliation(s)
- Chenyin Jiao
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, People's Republic of China
| | - Shenghai Pei
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, People's Republic of China
| | - Song Wu
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, People's Republic of China
| | - Zenghui Wang
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, People's Republic of China
| | - Juan Xia
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, People's Republic of China
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5
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Mesple F, Walet NR, Trambly de Laissardière G, Guinea F, Došenović D, Okuno H, Paillet C, Michon A, Chapelier C, Renard VT. Giant Atomic Swirl in Graphene Bilayers with Biaxial Heterostrain. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2306312. [PMID: 37615204 DOI: 10.1002/adma.202306312] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 08/10/2023] [Indexed: 08/25/2023]
Abstract
The study of moiré engineering started with the advent of van der Waals heterostructures, in which stacking 2D layers with different lattice constants leads to a moiré pattern controlling their electronic properties. The field entered a new era when it was found that adjusting the twist between two graphene layers led to strongly-correlated-electron physics and topological effects associated with atomic relaxation. A twist is now routinely used to adjust the properties of 2D materials. This study investigates a new type of moiré superlattice in bilayer graphene when one layer is biaxially strained with respect to the other-so-called biaxial heterostrain. Scanning tunneling microscopy measurements uncover spiraling electronic states associated with a novel symmetry-breaking atomic reconstruction at small biaxial heterostrain. Atomistic calculations using experimental parameters as inputs reveal that a giant atomic swirl forms around regions of aligned stacking to reduce the mechanical energy of the bilayer. Tight-binding calculations performed on the relaxed structure show that the observed electronic states decorate spiraling domain wall solitons as required by topology. This study establishes biaxial heterostrain as an important parameter to be harnessed for the next step of moiré engineering in van der Waals multilayers.
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Affiliation(s)
- Florie Mesple
- Univ. Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, Grenoble, 38000, France
| | - Niels R Walet
- Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PY, UK
| | - Guy Trambly de Laissardière
- Laboratoire de Physique Théorique et Modélisation (UMR 8089), CY Cergy Paris Université, CNRS, Cergy-Pontoise, 95302, France
| | - Francisco Guinea
- Imdea Nanoscience, Faraday 9, Madrid, 28015, Spain
- Donostia International Physics Center, Paseo Manuel de Lardizábal 4, San Sebastián, 20018, Spain
| | | | - Hanako Okuno
- University Grenoble Alpes, CEA, IRIG-MEM, Grenoble, 38054, France
| | - Colin Paillet
- Université Côte d'Azur, CNRS, CRHEA, Rue Bernard Grégory, Valbonne, 06560, France
| | - Adrien Michon
- Université Côte d'Azur, CNRS, CRHEA, Rue Bernard Grégory, Valbonne, 06560, France
| | - Claude Chapelier
- Univ. Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, Grenoble, 38000, France
| | - Vincent T Renard
- Univ. Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, Grenoble, 38000, France
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6
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Yan C, Zhao YX, Liu YW, He L. Kinetics of Nanobubbles in Tiny-Angle Twisted Bilayer Graphene. NANO LETTERS 2023; 23:8532-8538. [PMID: 37669559 DOI: 10.1021/acs.nanolett.3c02286] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/07/2023]
Abstract
Realization of high-quality van der Waals (vdWs) heterostructures by stacking two-dimensional (2D) layers requires atomically clean interfaces. Because of strong adhesion between the constituent layers, the vdWs forces could drive trapped contaminants together into submicron-size "bubbles", which leaves large interfacial areas atomically clean. Here, we study the kinetics of nanobubbles in tiny-angle twisted bilayer graphene (TBG) and our results reveal a substantial influence of the moiré superlattice on the motion of nanoscale interfacial substances. Our experiments indicate that the bubbles will mainly move along the triangular network of domain boundaries in the tiny-angle TBG when the sizes of the bubbles are comparable to that of an AA-stacking region. When the size of the bubble is smaller than that of an AA-stacking region, the bubble becomes motionless and is fixed in the AA-stacking region, because of its large out-of-plane corrugation.
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Affiliation(s)
- Chao Yan
- Center for Advanced Quantum Studies Department of Physics, Beijing Normal University, Beijing, 100875, China
- Key Laboratory of Multiscale Spin Physics, Ministry of Education, Beijing, 100875, China
| | - Ya-Xin Zhao
- Center for Advanced Quantum Studies Department of Physics, Beijing Normal University, Beijing, 100875, China
- Key Laboratory of Multiscale Spin Physics, Ministry of Education, Beijing, 100875, China
| | - Yi-Wen Liu
- Center for Advanced Quantum Studies Department of Physics, Beijing Normal University, Beijing, 100875, China
- Key Laboratory of Multiscale Spin Physics, Ministry of Education, Beijing, 100875, China
| | - Lin He
- Center for Advanced Quantum Studies Department of Physics, Beijing Normal University, Beijing, 100875, China
- Key Laboratory of Multiscale Spin Physics, Ministry of Education, Beijing, 100875, China
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7
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Molino L, Aggarwal L, Enaldiev V, Plumadore R, I Fal Ko V, Luican-Mayer A. Ferroelectric Switching at Symmetry-Broken Interfaces by Local Control of Dislocations Networks. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2207816. [PMID: 37377064 DOI: 10.1002/adma.202207816] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 06/06/2023] [Accepted: 06/15/2023] [Indexed: 06/29/2023]
Abstract
Semiconducting ferroelectric materials with low energy polarization switching offer a platform for next-generation electronics such as ferroelectric field-effect transistors. Recently discovered interfacial ferroelectricity in bilayers of transition metal dichalcogenide films provides an opportunity to combine the potential of semiconducting ferroelectrics with the design flexibility of 2D material devices. Here, local control of ferroelectric domains in a marginally twisted WS2 bilayer is demonstrated with a scanning tunneling microscope at room temperature, and their observed reversible evolution is understood using a string-like model of the domain wall network (DWN). Two characteristic regimes of DWN evolution are identified: (i) elastic bending of partial screw dislocations separating smaller domains with twin stackings due to mutual sliding of monolayers at domain boundaries and (ii) merging of primary domain walls into perfect screw dislocations, which become the seeds for the recovery of the initial domain structure upon reversing electric field. These results open the possibility to achieve full control over atomically thin semiconducting ferroelectric domains using local electric fields, which is a critical step towards their technological use.
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Affiliation(s)
- Laurent Molino
- Department of Physics, University of Ottawa, Ottawa, K1N 6N5, Canada
| | - Leena Aggarwal
- Department of Physics, University of Ottawa, Ottawa, K1N 6N5, Canada
| | - Vladimir Enaldiev
- Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK
| | - Ryan Plumadore
- Department of Physics, University of Ottawa, Ottawa, K1N 6N5, Canada
| | - Vladimir I Fal Ko
- Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK
- National Graphene Institute, University of Manchester, Manchester, M13 9PL, UK
- Henry Royce Institute for Advanced Materials, University of Manchester, Manchester, M13 9PL, UK
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8
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Kapfer M, Jessen BS, Eisele ME, Fu M, Danielsen DR, Darlington TP, Moore SL, Finney NR, Marchese A, Hsieh V, Majchrzak P, Jiang Z, Biswas D, Dudin P, Avila J, Watanabe K, Taniguchi T, Ulstrup S, Bøggild P, Schuck PJ, Basov DN, Hone J, Dean CR. Programming twist angle and strain profiles in 2D materials. Science 2023; 381:677-681. [PMID: 37561852 DOI: 10.1126/science.ade9995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 06/21/2023] [Indexed: 08/12/2023]
Abstract
Moiré superlattices in twisted two-dimensional materials have generated tremendous excitement as a platform for achieving quantum properties on demand. However, the moiré pattern is highly sensitive to the interlayer atomic registry, and current assembly techniques suffer from imprecise control of the average twist angle, spatial inhomogeneity in the local twist angle, and distortions caused by random strain. We manipulated the moiré patterns in hetero- and homobilayers through in-plane bending of monolayer ribbons, using the tip of an atomic force microscope. This technique achieves continuous variation of twist angles with improved twist-angle homogeneity and reduced random strain, resulting in moiré patterns with tunable wavelength and ultralow disorder. Our results may enable detailed studies of ultralow-disorder moiré systems and the realization of precise strain-engineered devices.
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Affiliation(s)
- Maëlle Kapfer
- Department of Physics, Columbia University, New York, NY, USA
| | - Bjarke S Jessen
- Department of Physics, Columbia University, New York, NY, USA
| | - Megan E Eisele
- Department of Physics, Columbia University, New York, NY, USA
| | - Matthew Fu
- Department of Physics, Columbia University, New York, NY, USA
| | - Dorte R Danielsen
- Center for Nanostructured Graphene, Technical University of Denmark, DK-2800, Denmark
- DTU Physics, Technical University of Denmark, DK-2800, Denmark
| | - Thomas P Darlington
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - Samuel L Moore
- Department of Physics, Columbia University, New York, NY, USA
| | - Nathan R Finney
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - Ariane Marchese
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - Valerie Hsieh
- Department of Physics, Columbia University, New York, NY, USA
| | - Paulina Majchrzak
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - Zhihao Jiang
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - Deepnarayan Biswas
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - Pavel Dudin
- Synchrotron SOLEIL, Université Paris-Saclay, F-91192 Gif sur Yvette, France
| | - José Avila
- Synchrotron SOLEIL, Université Paris-Saclay, F-91192 Gif sur Yvette, France
| | - Kenji Watanabe
- National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Takashi Taniguchi
- National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Søren Ulstrup
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - Peter Bøggild
- Center for Nanostructured Graphene, Technical University of Denmark, DK-2800, Denmark
- DTU Physics, Technical University of Denmark, DK-2800, Denmark
| | - P J Schuck
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - Dmitri N Basov
- Department of Physics, Columbia University, New York, NY, USA
| | - James Hone
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - Cory R Dean
- Department of Physics, Columbia University, New York, NY, USA
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9
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Chen X, Xu S, Shabani S, Zhao Y, Fu M, Millis AJ, Fogler MM, Pasupathy AN, Liu M, Basov DN. Machine Learning for Optical Scanning Probe Nanoscopy. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2109171. [PMID: 36333118 DOI: 10.1002/adma.202109171] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 07/09/2022] [Indexed: 06/16/2023]
Abstract
The ability to perform nanometer-scale optical imaging and spectroscopy is key to deciphering the low-energy effects in quantum materials, as well as vibrational fingerprints in planetary and extraterrestrial particles, catalytic substances, and aqueous biological samples. These tasks can be accomplished by the scattering-type scanning near-field optical microscopy (s-SNOM) technique that has recently spread to many research fields and enabled notable discoveries. Herein, it is shown that the s-SNOM, together with scanning probe research in general, can benefit in many ways from artificial-intelligence (AI) and machine-learning (ML) algorithms. Augmented with AI- and ML-enhanced data acquisition and analysis, scanning probe optical nanoscopy is poised to become more efficient, accurate, and intelligent.
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Affiliation(s)
- Xinzhong Chen
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Suheng Xu
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Sara Shabani
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Yueqi Zhao
- Department of Physics, University of California at San Diego, La Jolla, CA, 92093-0319, USA
| | - Matthew Fu
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Andrew J Millis
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Michael M Fogler
- Department of Physics, University of California at San Diego, La Jolla, CA, 92093-0319, USA
| | - Abhay N Pasupathy
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Mengkun Liu
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - D N Basov
- Department of Physics, Columbia University, New York, NY, 10027, USA
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10
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Canetta A, Gonzalez-Munoz S, Nguyen VH, Agarwal K, de Crombrugghe de Picquendaele P, Hong Y, Mohapatra S, Watanabe K, Taniguchi T, Nysten B, Hackens B, Ribeiro-Palau R, Charlier JC, Kolosov OV, Spièce J, Gehring P. Quantifying the local mechanical properties of twisted double bilayer graphene. NANOSCALE 2023; 15:8134-8140. [PMID: 36974920 DOI: 10.1039/d3nr00388d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Nanomechanical measurements of minimally twisted van der Waals materials remained elusive despite their fundamental importance for device realisation. Here, we use Ultrasonic Force Microscopy (UFM) to locally quantify the variation of out-of-plane Young's modulus in minimally twisted double bilayer graphene (TDBG). We reveal a softening of the Young's modulus by 7% and 17% along single and double domain walls, respectively. Our experimental results are confirmed by force-field relaxation models. This study highlights the strong tunability of nanomechanical properties in engineered twisted materials, and paves the way for future applications of designer 2D nanomechanical systems.
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Affiliation(s)
- Alessandra Canetta
- Institute of Condensed Matter and Nanosciences, Université catholique de Louvain (UCLouvain), 1348 Louvain-la-Neuve, Belgium.
| | | | - Viet-Hung Nguyen
- Institute of Condensed Matter and Nanosciences, Université catholique de Louvain (UCLouvain), 1348 Louvain-la-Neuve, Belgium.
| | | | | | - Yuanzhuo Hong
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies (C2N), 91120 Palaiseau, France
| | - Sambit Mohapatra
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies (C2N), 91120 Palaiseau, France
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Namiki 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Namiki 305-0044, Japan
| | - Bernard Nysten
- Institute of Condensed Matter and Nanosciences, Université catholique de Louvain (UCLouvain), 1348 Louvain-la-Neuve, Belgium.
| | - Benoît Hackens
- Institute of Condensed Matter and Nanosciences, Université catholique de Louvain (UCLouvain), 1348 Louvain-la-Neuve, Belgium.
| | - Rebeca Ribeiro-Palau
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies (C2N), 91120 Palaiseau, France
| | - Jean-Christophe Charlier
- Institute of Condensed Matter and Nanosciences, Université catholique de Louvain (UCLouvain), 1348 Louvain-la-Neuve, Belgium.
| | | | - Jean Spièce
- Institute of Condensed Matter and Nanosciences, Université catholique de Louvain (UCLouvain), 1348 Louvain-la-Neuve, Belgium.
| | - Pascal Gehring
- Institute of Condensed Matter and Nanosciences, Université catholique de Louvain (UCLouvain), 1348 Louvain-la-Neuve, Belgium.
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11
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Hsieh V, Halbertal D, Finney NR, Zhu Z, Gerber E, Pizzochero M, Kucukbenli E, Schleder GR, Angeli M, Watanabe K, Taniguchi T, Kim EA, Kaxiras E, Hone J, Dean CR, Basov DN. Domain-Dependent Surface Adhesion in Twisted Few-Layer Graphene: Platform for Moiré-Assisted Chemistry. NANO LETTERS 2023; 23:3137-3143. [PMID: 37036942 DOI: 10.1021/acs.nanolett.2c04137] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Twisted van der Waals multilayers are widely regarded as a rich platform to access novel electronic phases thanks to the multiple degrees of freedom available for controlling their electronic and chemical properties. Here, we propose that the stacking domains that form naturally due to the relative twist between successive layers act as an additional "knob" for controlling the behavior of these systems and report the emergence and engineering of stacking domain-dependent surface chemistry in twisted few-layer graphene. Using mid-infrared near-field optical microscopy and atomic force microscopy, we observe a selective adhesion of metallic nanoparticles and liquid water at the domains with rhombohedral stacking configurations of minimally twisted double bi- and trilayer graphene. Furthermore, we demonstrate that the manipulation of nanoparticles located at certain stacking domains can locally reconfigure the moiré superlattice in their vicinity at the micrometer scale. Our findings establish a new approach to controlling moiré-assisted chemistry and nanoengineering.
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Affiliation(s)
- Valerie Hsieh
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Dorri Halbertal
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Nathan R Finney
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Ziyan Zhu
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Eli Gerber
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States
| | - Michele Pizzochero
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Emine Kucukbenli
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
- Information Systems Department, Boston University, Boston, Massachusetts 02215, United States
| | - Gabriel R Schleder
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
- Brazilian Nanotechnology National Laboratory, CNPEM, Campinas 13083-970, São Paulo, Brazil
| | - Mattia Angeli
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Eun-Ah Kim
- Department of Physics, Cornell University, Ithaca, New York 14853, United States
| | - Efthimios Kaxiras
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - James Hone
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Cory R Dean
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - D N Basov
- Department of Physics, Columbia University, New York, New York 10027, United States
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12
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Zhang S, Maruyama M, Okada S, Xue M, Watanabe K, Taniguchi T, Hashimoto K, Miyata Y, Canton-Vitoria R, Kitaura R. Observation of the photovoltaic effect in a van der Waals heterostructure. NANOSCALE 2023; 15:5948-5953. [PMID: 36883438 DOI: 10.1039/d2nr06616e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
van der Waals (vdW) heterostructures, which can be assembled with various two-dimensional materials, provide a versatile platform for exploring emergent phenomena. Here, we report an observation of the photovoltaic effect in a WS2/MoS2 vdW heterostructure. Light excitation of WS2/MoS2 at a wavelength of 633 nm yields a photocurrent without applying bias voltages, and the excitation power dependence of the photocurrent shows characteristic crossover from a linear to square root dependence. Photocurrent mapping has clearly shown that the observed photovoltaic effect arises from the WS2/MoS2 region, not from Schottky junctions at electrode contacts. Kelvin probe microscopy observations show no slope in the electrostatic potential, excluding the possibility that the photocurrent originates from an unintentionally formed built-in potential.
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Affiliation(s)
- Shaochun Zhang
- Department of Chemistry, Nagoya University, Nagoya, Aichi 464-8602, Japan.
| | - Mina Maruyama
- Department of Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8571, Japan
| | - Susumu Okada
- Department of Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8571, Japan
| | - Mengsong Xue
- Department of Chemistry, Nagoya University, Nagoya, Aichi 464-8602, Japan.
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Kazuki Hashimoto
- Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
| | - Yasumitsu Miyata
- Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
| | | | - Ryo Kitaura
- Department of Chemistry, Nagoya University, Nagoya, Aichi 464-8602, Japan.
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
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13
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Wang Y, Song Z, Wan J, Betzler S, Xie Y, Ophus C, Bustillo KC, Ercius P, Wang LW, Zheng H. Strong Structural and Electronic Coupling in Metavalent PbS Moiré Superlattices. J Am Chem Soc 2022; 144:23474-23482. [PMID: 36512727 DOI: 10.1021/jacs.2c09947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Moiré superlattices are twisted bilayer materials in which the tunable interlayer quantum confinement offers access to new physics and novel device functionalities. Previously, moiré superlattices were built exclusively using materials with weak van der Waals interactions, and synthesizing moiré superlattices with strong interlayer chemical bonding was considered to be impractical. Here, using lead sulfide (PbS) as an example, we report a strategy for synthesizing moiré superlattices coupled by strong chemical bonding. We use water-soluble ligands as a removable template to obtain free-standing ultrathin PbS nanosheets and assemble them into direct-contact bilayers with various twist angles. Atomic-resolution imaging shows the moiré periodic structural reconstruction at the superlattice interface due to the strong metavalent coupling. Electron energy loss spectroscopy and theoretical calculations collectively reveal the twist-angle-dependent electronic structure, especially the emergent separation of flat bands at small twist angles. The localized states of flat bands are similar to well-arranged quantum dots, promising an application in devices. This study opens a new door to the exploration of deep energy modulations within moiré superlattices alternative to van der Waals twistronics.
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Affiliation(s)
- Yu Wang
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States.,Center for Electron Microscopy and South China Advanced Institute for Soft Matter Science and Technology, School of Emergent Soft Matter, South China University of Technology, Guangzhou510640, China
| | - Zhigang Song
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts02138, United States
| | - Jiawei Wan
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States.,Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, California94720, United States
| | - Sophia Betzler
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Yujun Xie
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Colin Ophus
- National Center for Electron Microscopy, The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Karen C Bustillo
- National Center for Electron Microscopy, The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Peter Ercius
- National Center for Electron Microscopy, The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Lin-Wang Wang
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Haimei Zheng
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States.,Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, California94720, United States
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14
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El-Sayed MA, Tselin AP, Ermolaev GA, Tatmyshevskiy MK, Slavich AS, Yakubovsky DI, Novikov SM, Vyshnevyy AA, Arsenin AV, Volkov VS. Non-Additive Optical Response in Transition Metal Dichalcogenides Heterostructures. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:nano12244436. [PMID: 36558289 PMCID: PMC9787828 DOI: 10.3390/nano12244436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 12/04/2022] [Accepted: 12/09/2022] [Indexed: 05/27/2023]
Abstract
Van der Waals (vdW) heterostructures pave the way to achieve the desired material properties for a variety of applications. In this way, new scientific and industrial challenges and fundamental questions arise. One of them is whether vdW materials preserve their original optical response when assembled in a heterostructure. Here, we resolve this issue for four exemplary monolayer heterostructures: MoS2/Gr, MoS2/hBN, WS2/Gr, and WS2/hBN. Through joint Raman, ellipsometry, and reflectance spectroscopies, we discovered that heterostructures alter MoS2 and WS2 optical constants. Furthermore, despite the similarity of MoS2 and WS2 monolayers, their behavior in heterostructures is markedly different. While MoS2 has large changes, particularly above 3 eV, WS2 experiences modest changes in optical constants. We also detected a transformation from dark into bright exciton for MoS2/Gr heterostructure. In summary, our findings provide clear evidence that the optical response of heterostructures is not the sum of optical properties of its constituents.
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Affiliation(s)
- Marwa A. El-Sayed
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700, Russia
- Department of Physics, Faculty of Science, Menoufia University, Shebin El-Koom 32511, Egypt
| | - Andrey P. Tselin
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700, Russia
- Photonics and Quantum Materials Department, Skolkovo Institute of Science and Technology, 3 Nobel, Moscow 143026, Russia
| | - Georgy A. Ermolaev
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700, Russia
| | - Mikhail K. Tatmyshevskiy
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700, Russia
| | - Aleksandr S. Slavich
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700, Russia
| | - Dmitry I. Yakubovsky
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700, Russia
| | - Sergey M. Novikov
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700, Russia
| | - Andrey A. Vyshnevyy
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700, Russia
| | - Aleksey V. Arsenin
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700, Russia
| | - Valentyn S. Volkov
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700, Russia
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15
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Halbertal D, Turkel S, Ciccarino CJ, Profe JB, Finney N, Hsieh V, Watanabe K, Taniguchi T, Hone J, Dean C, Narang P, Pasupathy AN, Kennes DM, Basov DN. Unconventional non-local relaxation dynamics in a twisted trilayer graphene moiré superlattice. Nat Commun 2022; 13:7587. [PMID: 36481831 PMCID: PMC9731949 DOI: 10.1038/s41467-022-35213-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 11/18/2022] [Indexed: 12/13/2022] Open
Abstract
The electronic and structural properties of atomically thin materials can be controllably tuned by assembling them with an interlayer twist. During this process, constituent layers spontaneously rearrange themselves in search of a lowest energy configuration. Such relaxation phenomena can lead to unexpected and novel material properties. Here, we study twisted double trilayer graphene (TDTG) using nano-optical and tunneling spectroscopy tools. We reveal a surprising optical and electronic contrast, as well as a stacking energy imbalance emerging between the moiré domains. We attribute this contrast to an unconventional form of lattice relaxation in which an entire graphene layer spontaneously shifts position during assembly, resulting in domains of ABABAB and BCBACA stacking. We analyze the energetics of this transition and demonstrate that it is the result of a non-local relaxation process, in which an energy gain in one domain of the moiré lattice is paid for by a relaxation that occurs in the other.
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Affiliation(s)
- Dorri Halbertal
- Department of Physics, Columbia University, New York, NY, 10027, USA.
| | - Simon Turkel
- Department of Physics, Columbia University, New York, NY, 10027, USA
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Christopher J Ciccarino
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA
| | - Jonas B Profe
- Institute for Theory of Statistical Physics, RWTH Aachen University, and JARA Fundamentals of Future Information Technology, 52062, Aachen, Germany
| | - Nathan Finney
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Valerie Hsieh
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - James Hone
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Cory Dean
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Prineha Narang
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA
| | - Abhay N Pasupathy
- Department of Physics, Columbia University, New York, NY, 10027, USA
- Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Dante M Kennes
- Institute for Theory of Statistical Physics, RWTH Aachen University, and JARA Fundamentals of Future Information Technology, 52062, Aachen, Germany
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Hamburg, Germany
| | - D N Basov
- Department of Physics, Columbia University, New York, NY, 10027, USA
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16
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Lv M, Sun X, Chen Y, Taniguchi T, Watanabe K, Wu M, Wang J, Xue J. Spatially Resolved Polarization Manipulation of Ferroelectricity in Twisted hBN. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2203990. [PMID: 36271514 DOI: 10.1002/adma.202203990] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 09/29/2022] [Indexed: 06/16/2023]
Abstract
Robust room-temperature interfacial ferroelectricity has been formed in the 2D limit by simply twisting two atomic layers of non-ferroelectric hexagonal boron nitride (hBN). A thorough understanding of this newly discovered ferroelectric system is required. Here, twisted hBN is used as a tunneling junction and it is studied at the nanometer scale using conductive atomic force microscopy. Three properties unique to this system are discovered. First, the polarization dependence of the tunneling resistance contrasts with the conventional theory. Second, the ferroelectric domains can be controlled using mechanical stress, highlighting the original meaning of the emergent "slidetronics". Third, ferroelectric hysteresis is highly spatially dependent. The hysteresis is symmetric at the domain walls. A few nanometers away, the hysteresis shifts completely to the positive or negative side, depending on the original polarization. These findings reveal the unconventional ferroelectricity in this 2D system.
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Affiliation(s)
- Ming Lv
- School of Physical Science and Technology, ShanghaiTech University, Pudong, Shanghai, 201210, China
| | - Xinzuo Sun
- School of Physical Science and Technology, ShanghaiTech University, Pudong, Shanghai, 201210, China
| | - Yan Chen
- Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Hongkou, Shanghai, 200083, China
- Frontier Institute of Chip and System, Institute of Optoelectronics, Shanghai Frontier Base of Intelligent Optoelectronics and Perception, Fudan University, Shanghai, 200438, China
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Menghao Wu
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Jianlu Wang
- Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Hongkou, Shanghai, 200083, China
- Frontier Institute of Chip and System, Institute of Optoelectronics, Shanghai Frontier Base of Intelligent Optoelectronics and Perception, Fudan University, Shanghai, 200438, China
| | - Jiamin Xue
- School of Physical Science and Technology, ShanghaiTech University, Pudong, Shanghai, 201210, China
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17
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Wirth KG, Hauck JB, Rothstein A, Kyoseva H, Siebenkotten D, Conrads L, Klebl L, Fischer A, Beschoten B, Stampfer C, Kennes DM, Waldecker L, Taubner T. Experimental Observation of ABCB Stacked Tetralayer Graphene. ACS NANO 2022; 16:16617-16623. [PMID: 36205460 DOI: 10.1021/acsnano.2c06053] [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
In tetralayer graphene, three inequivalent layer stackings should exist; however, only rhombohedral (ABCA) and Bernal (ABAB) stacking have so far been observed. The three stacking sequences differ in their electronic structure, with the elusive third stacking (ABCB) being unique as it is predicted to exhibit an intrinsic bandgap as well as locally flat bands around the K points. Here, we use scattering-type scanning near-field optical microscopy and confocal Raman microscopy to identify and characterize domains of ABCB stacked tetralayer graphene. We differentiate between the three stacking sequences by addressing characteristic interband contributions in the optical conductivity between 0.28 and 0.56 eV with amplitude and phase-resolved near-field nanospectroscopy. By normalizing adjacent flakes to each other, we achieve good agreement between theory and experiment, allowing for the unambiguous assignment of ABCB domains in tetralayer graphene. These results establish near-field spectroscopy at the interband transitions as a semiquantitative tool, enabling the recognition of ABCB domains in tetralayer graphene flakes and, therefore, providing a basis to study correlation physics of this exciting phase.
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Affiliation(s)
- Konstantin G Wirth
- 1st Institute of Physics (IA), RWTH Aachen University, 52074 Aachen, Germany
| | - Jonas B Hauck
- Institute for Theory of Statistical Physics, RWTH Aachen University and JARA Fundamentals of Future Information Technology, 52062 Aachen, Germany
| | - Alexander Rothstein
- 2nd Institute of Physics and JARA-FIT, RWTH Aachen University, 52074 Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Hristiyana Kyoseva
- 2nd Institute of Physics and JARA-FIT, RWTH Aachen University, 52074 Aachen, Germany
| | - Dario Siebenkotten
- 1st Institute of Physics (IA), RWTH Aachen University, 52074 Aachen, Germany
| | - Lukas Conrads
- 1st Institute of Physics (IA), RWTH Aachen University, 52074 Aachen, Germany
| | - Lennart Klebl
- Institute for Theory of Statistical Physics, RWTH Aachen University and JARA Fundamentals of Future Information Technology, 52062 Aachen, Germany
| | - Ammon Fischer
- Institute for Theory of Statistical Physics, RWTH Aachen University and JARA Fundamentals of Future Information Technology, 52062 Aachen, Germany
| | - Bernd Beschoten
- 2nd Institute of Physics and JARA-FIT, RWTH Aachen University, 52074 Aachen, Germany
| | - Christoph Stampfer
- 2nd Institute of Physics and JARA-FIT, RWTH Aachen University, 52074 Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Dante M Kennes
- Institute for Theory of Statistical Physics, RWTH Aachen University and JARA Fundamentals of Future Information Technology, 52062 Aachen, Germany
- Center for Free Electron Laser Science, Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - Lutz Waldecker
- 2nd Institute of Physics and JARA-FIT, RWTH Aachen University, 52074 Aachen, Germany
| | - Thomas Taubner
- 1st Institute of Physics (IA), RWTH Aachen University, 52074 Aachen, Germany
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18
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Song Z, Wang Y, Zheng H, Narang P, Wang LW. Deep Quantum-Dot Arrays in Moiré Superlattices of Non-van der Waals Materials. J Am Chem Soc 2022; 144:14657-14667. [PMID: 35921553 DOI: 10.1021/jacs.2c04390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recently, moiré superlattices of twisted van der Waals (vdW) materials have attracted substantial interest due to their strongly correlated properties. However, the vdW interlayer interaction is intrinsically weak, such that many desired properties can only exist at low temperature. Here, we theoretically predict some unusual properties stemming from the chemical bonding between twisted PbS nanosheets as an example of non-vdW moiré superlattices. The strong interlayer coupling in such systems results in giant strain vortices and dipole vortices at the interface. The modified electronic structures become a series of dispersionless bands and artificial-atom states. In real space, these states are analogous to arrays of well-positioned quantum dots, which may be promising for use in single-electron devices. In theory, if the materials are doped with a low concentration of electrons, a Wigner crystal will form even without any magnetic field. To confirm the accessibility and stability of non-vdW moiré superlattices in experiment, we synthesized PbS moiré superlattices with different twist angles. Our transmission-electron-microscope observations reveal the resemblance of the small-angle-twisted structures with the square matrices of quantum dots, which is in good accordance with our calculations.
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Affiliation(s)
- Zhigang Song
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Yu Wang
- South China Advanced Institute for Soft Matter Science and Technology, School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
| | - Haimei Zheng
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.,Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States
| | - Prineha Narang
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Lin-Wang Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
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19
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Wang X, Zhao Y, Kong X, Zhang Q, Ng HK, Lim SX, Zheng Y, Wu X, Watanabe K, Xu QH, Taniguchi T, Eda G, Goh KEJ, Jin S, Loh KP, Ding F, Sun W, Sow CH. Dynamic Tuning of Moiré Superlattice Morphology by Laser Modification. ACS NANO 2022; 16:8172-8180. [PMID: 35575066 DOI: 10.1021/acsnano.2c01625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In artificial van der Waals (vdW) layered devices, twisting the stacking angle has emerged as an effective strategy to regulate the electronic phases and optical properties of these systems. Along with the twist registry, the lattice reconstruction arising from vdW interlayer interaction has also inspired significant research interests. The control of twist angles is significantly important because the moiré periodicity determines the electron propagation length on the lattice and the interlayer electron-electron interactions. However, the moiré periodicity is hard to be modified after the device has been fabricated. In this work, we have demonstrated that the moiré periodicity can be precisely modulated with a localized laser annealing technique. This is achieved with regulating the interlayer lattice mismatch by the mismatched lattice constant, which originates from the variable density of sulfur vacancy generated during laser modification. The existence of sulfur vacancy is further verified by excitonic emission energy and lifetime in photoluminescence measurements. Furthermore, we also discover that the mismatched lattice constant has the equivalent contribution as the twist angle for determining the lattice mismatch. Theoretical modeling elaborates the moiré-wavelength-dependent energy variations at the interface and mimics the evolution of moiré morphology.
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Affiliation(s)
- Xinyun Wang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546
| | - Yuzhou Zhao
- Department of Chemistry, University of Wisconsin─Madison, Madison, Wisconsin 53706, United States
| | - Xiao Kong
- Centre for Multidimensional Carbon Materials, Institute for Basic Science, Ulsan, Korea 44919
| | - Qi Zhang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
| | - Hong Kuan Ng
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
| | - Sharon Xiaodai Lim
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
| | - Yue Zheng
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546
| | - Xiao Wu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Namiki Tsukuba, Ibaraki Japan 305-0044
| | - Qing-Hua Xu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Namiki Tsukuba, Ibaraki Japan 305-0044
| | - Goki Eda
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
| | - Kuan Eng Johnson Goh
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Singapore 138634
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371
| | - Song Jin
- Department of Chemistry, University of Wisconsin─Madison, Madison, Wisconsin 53706, United States
| | - Kian Ping Loh
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
| | - Feng Ding
- Centre for Multidimensional Carbon Materials, Institute for Basic Science, Ulsan, Korea 44919
| | - Wanxin Sun
- Bruker Nano Surface Division, 30 Biopolis Street 09-01, The Matrix, Singapore 138671
| | - Chorng Haur Sow
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546
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20
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Siday T, Sandner F, Brem S, Zizlsperger M, Perea-Causin R, Schiegl F, Nerreter S, Plankl M, Merkl P, Mooshammer F, Huber MA, Malic E, Huber R. Ultrafast Nanoscopy of High-Density Exciton Phases in WSe 2. NANO LETTERS 2022; 22:2561-2568. [PMID: 35157466 DOI: 10.1021/acs.nanolett.1c04741] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The density-driven transition of an exciton gas into an electron-hole plasma remains a compelling question in condensed matter physics. In two-dimensional transition metal dichalcogenides, strongly bound excitons can undergo this phase change after transient injection of electron-hole pairs. Unfortunately, unavoidable nanoscale inhomogeneity in these materials has impeded quantitative investigation into this elusive transition. Here, we demonstrate how ultrafast polarization nanoscopy can capture the Mott transition through the density-dependent recombination dynamics of electron-hole pairs within a WSe2 homobilayer. For increasing carrier density, an initial monomolecular recombination of optically dark excitons transitions continuously into a bimolecular recombination of an unbound electron-hole plasma above 7 × 1012 cm-2. We resolve how the Mott transition modulates over nanometer length scales, directly evidencing the strong inhomogeneity in stacked monolayers. Our results demonstrate how ultrafast polarization nanoscopy could unveil the interplay of strong electronic correlations and interlayer coupling within a diverse range of stacked and twisted two-dimensional materials.
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Affiliation(s)
- Thomas Siday
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
| | - Fabian Sandner
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
| | - Samuel Brem
- Department of Physics, Philipps-Universität Marburg, 35032 Marburg, Germany
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Martin Zizlsperger
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
| | - Raul Perea-Causin
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Felix Schiegl
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
| | - Svenja Nerreter
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
| | - Markus Plankl
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
| | - Philipp Merkl
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
| | - Fabian Mooshammer
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Markus A Huber
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
| | - Ermin Malic
- Department of Physics, Philipps-Universität Marburg, 35032 Marburg, Germany
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Rupert Huber
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
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21
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Huang D, Choi J, Shih CK, Li X. Excitons in semiconductor moiré superlattices. NATURE NANOTECHNOLOGY 2022; 17:227-238. [PMID: 35288673 DOI: 10.1038/s41565-021-01068-y] [Citation(s) in RCA: 58] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 12/06/2021] [Indexed: 06/14/2023]
Abstract
Semiconductor moiré superlattices represent a rapidly developing area of engineered photonic materials and a new platform to explore correlated electron states and quantum simulation. In this Review, we briefly introduce early experiments that identified new exciton resonances in transition metal dichalcogenide heterobilayers and discuss several topics including two types of transition metal dichalcogenide moiré superlattice, new optical selection rules, early evidence of moiré excitons, and how the resonant energy, dynamics and diffusion properties of moiré excitons can be controlled via the twist angle. To interpret optical spectra, it is important to measure the energy modulation within a moiré supercell. In this context, we describe a few scanning tunnelling microscopy experiments that measure the moiré potential landscape directly. Finally, we review a few recent experiments that applied excitonic optical spectroscopy to probe correlated electron phenomena in transition metal dichalcogenide moiré superlattices.
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Affiliation(s)
- Di Huang
- Physics Department and Center for Complex Quantum Systems, The University of Texas-Austin, Austin, TX, USA.
| | - Junho Choi
- Physics Department and Center for Complex Quantum Systems, The University of Texas-Austin, Austin, TX, USA
- Texas Materials Institute and Center for Dynamics and Control of Materials, The University of Texas-Austin, Austin, TX, USA
| | - Chih-Kang Shih
- Physics Department and Center for Complex Quantum Systems, The University of Texas-Austin, Austin, TX, USA
- Texas Materials Institute and Center for Dynamics and Control of Materials, The University of Texas-Austin, Austin, TX, USA
| | - Xiaoqin Li
- Physics Department and Center for Complex Quantum Systems, The University of Texas-Austin, Austin, TX, USA.
- Texas Materials Institute and Center for Dynamics and Control of Materials, The University of Texas-Austin, Austin, TX, USA.
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22
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Halbertal D, Shabani S, Passupathy AN, Basov DN. Extracting the Strain Matrix and Twist Angle from the Moiré Superlattice in van der Waals Heterostructures. ACS NANO 2022; 16:1471-1476. [PMID: 34982529 DOI: 10.1021/acsnano.1c09789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
When two atomic layers are brought into contact at a relative twist angle, a large-scale pattern, called a moiré superlattice, emerges due to the (angular or lattice) mismatch between the layers. This has profound consequences in terms of the Hamiltonian of the system but was also considered in several publications as a means to extract the local strain tensor. While extracting the twist angle based on knowledge of the periodicity of the moiré is trivial in the case of a regular moiré pattern, in many examples in the literature, that is not the case. In particular, extracting the strain tensor and twist angle maps from a spatially varying moiré pattern is not straightforward. This article aims to provide a practical tool to extract the strain tensor and twist angle from an experimentally observable pattern. It further addresses the limitation of any such approach in the absence of additional experimental information beyond the moiré superlattice pattern.
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Affiliation(s)
- Dorri Halbertal
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Sara Shabani
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Abhay N Passupathy
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - D N Basov
- Department of Physics, Columbia University, New York, New York 10027, United States
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23
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de Jong TA, Benschop T, Chen X, Krasovskii EE, de Dood MJA, Tromp RM, Allan MP, van der Molen SJ. Imaging moiré deformation and dynamics in twisted bilayer graphene. Nat Commun 2022; 13:70. [PMID: 35013349 PMCID: PMC8748992 DOI: 10.1038/s41467-021-27646-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 12/03/2021] [Indexed: 11/22/2022] Open
Abstract
In 'magic angle' twisted bilayer graphene (TBG) a flat band forms, yielding correlated insulator behavior and superconductivity. In general, the moiré structure in TBG varies spatially, influencing the overall conductance properties of devices. Hence, to understand the wide variety of phase diagrams observed, a detailed understanding of local variations is needed. Here, we study spatial and temporal variations of the moiré pattern in TBG using aberration-corrected Low Energy Electron Microscopy (AC-LEEM). We find a smaller spatial variation than reported previously. Furthermore, we observe thermal fluctuations corresponding to collective atomic displacements over 70 pm on a timescale of seconds. Remarkably, no untwisting is found up to 600 ∘C. We conclude that thermal annealing can be used to decrease local disorder. Finally, we observe edge dislocations in the underlying atomic lattice, the moiré structure acting as a magnifying glass. These topological defects are anticipated to exhibit unique local electronic properties.
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Affiliation(s)
- Tobias A de Jong
- Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA, Leiden, The Netherlands.
| | - Tjerk Benschop
- Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA, Leiden, The Netherlands
| | - Xingchen Chen
- Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA, Leiden, The Netherlands
| | - Eugene E Krasovskii
- Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología, Universidad del Pais Vasco UPV/EHU, 20080, San Sebastián/Donostia, Spain
- IKERBASQUE, Basque Foundation for Science, E-48013, Bilbao, Spain
- Donostia International Physics Center (DIPC), E-20018, San Sebastián, Spain
| | - Michiel J A de Dood
- Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA, Leiden, The Netherlands
| | - Rudolf M Tromp
- Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA, Leiden, The Netherlands
- IBM T.J.Watson Research Center, 1101 Kitchawan Road, P.O. Box 218, Yorktown Heights, New York, NY, 10598, USA
| | - Milan P Allan
- Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA, Leiden, The Netherlands
| | - Sense Jan van der Molen
- Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA, Leiden, The Netherlands.
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24
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Jeong JH, Kang S, Kim N, Joshi RK, Lee GH. Recent trends in covalent functionalization of 2D materials. Phys Chem Chem Phys 2022; 24:10684-10711. [DOI: 10.1039/d1cp04831g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Covalent functionalization of the surface is more crucial in 2D materials than in conventional bulk materials because of their atomic thinness, large surface-to-volume ratio, and uniform surface chemical potential. Because...
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25
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Moore SL, Ciccarino CJ, Halbertal D, McGilly LJ, Finney NR, Yao K, Shao Y, Ni G, Sternbach A, Telford EJ, Kim BS, Rossi SE, Watanabe K, Taniguchi T, Pasupathy AN, Dean CR, Hone J, Schuck PJ, Narang P, Basov DN. Nanoscale lattice dynamics in hexagonal boron nitride moiré superlattices. Nat Commun 2021; 12:5741. [PMID: 34593793 PMCID: PMC8484559 DOI: 10.1038/s41467-021-26072-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 09/02/2021] [Indexed: 11/12/2022] Open
Abstract
Twisted two-dimensional van der Waals (vdW) heterostructures have unlocked a new means for manipulating the properties of quantum materials. The resulting mesoscopic moiré superlattices are accessible to a wide variety of scanning probes. To date, spatially-resolved techniques have prioritized electronic structure visualization, with lattice response experiments only in their infancy. Here, we therefore investigate lattice dynamics in twisted layers of hexagonal boron nitride (hBN), formed by a minute twist angle between two hBN monolayers assembled on a graphite substrate. Nano-infrared (nano-IR) spectroscopy reveals systematic variations of the in-plane optical phonon frequencies amongst the triangular domains and domain walls in the hBN moiré superlattices. Our first-principles calculations unveil a local and stacking-dependent interaction with the underlying graphite, prompting symmetry-breaking between the otherwise identical neighboring moiré domains of twisted hBN. Here, the authors investigate the lattice dynamics of twisted hexagonal boron nitride layers via nano-infrared spectroscopy, showing local and stacking-dependent variations of the optical phonon frequencies associated to the interaction with the graphite substrate.
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Affiliation(s)
- S L Moore
- Department of Physics, Columbia University, New York, NY, USA.
| | - C J Ciccarino
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - D Halbertal
- Department of Physics, Columbia University, New York, NY, USA
| | - L J McGilly
- Department of Physics, Columbia University, New York, NY, USA
| | - N R Finney
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - K Yao
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - Y Shao
- Department of Physics, Columbia University, New York, NY, USA
| | - G Ni
- Department of Physics, Columbia University, New York, NY, USA
| | - A Sternbach
- Department of Physics, Columbia University, New York, NY, USA
| | - E J Telford
- Department of Physics, Columbia University, New York, NY, USA
| | - B S Kim
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - S E Rossi
- Department of Physics, Columbia University, New York, NY, USA
| | - K Watanabe
- National Institute for Materials Science, 1-1 Namiki, Tsukuba, Japan
| | - T Taniguchi
- National Institute for Materials Science, 1-1 Namiki, Tsukuba, Japan
| | - A N Pasupathy
- Department of Physics, Columbia University, New York, NY, USA
| | - C R Dean
- Department of Physics, Columbia University, New York, NY, USA
| | - J Hone
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - P J Schuck
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - P Narang
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - D N Basov
- Department of Physics, Columbia University, New York, NY, USA
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26
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Xian L, Fischer A, Claassen M, Zhang J, Rubio A, Kennes DM. Engineering Three-Dimensional Moiré Flat Bands. NANO LETTERS 2021; 21:7519-7526. [PMID: 34516114 PMCID: PMC8461648 DOI: 10.1021/acs.nanolett.1c01684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 08/25/2021] [Indexed: 06/13/2023]
Abstract
Twisting two adjacent layers of van der Waals materials with respect to each other can lead to flat two-dimensional electronic bands which enables a wealth of physical phenomena. Here, we generalize this concept of so-called moiré flat bands to engineer flat bands in all three spatial dimensions controlled by the twist angle. The basic concept is to stack the material such that the large spatial moiré interference patterns are spatially shifted from one twisted layer to the next. We exemplify the general concept by considering graphitic systems, boron nitride, and WSe2, but the approach is applicable to any two-dimensional van der Waals material. For hexagonal boron nitride, we develop an ab initio fitted tight binding model that captures the corresponding three-dimensional low-energy electronic structure. We outline that interesting three-dimensional correlated phases of matter can be induced and controlled following this route, including quantum magnets and unconventional superconducting states.
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Affiliation(s)
- Lede Xian
- Songshan
Lake Materials Laboratory, 523808 Dongguan, Guangdong China
- Center
for Free Electron Laser Science, Max Planck
Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - Ammon Fischer
- Institut
für Theorie der Statistischen Physik, RWTH Aachen University and JARA-Fundamentals of Future Information
Technology, 52056 Aachen, Germany
| | - Martin Claassen
- Department
of Physics and Astronomy, University of
Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Jin Zhang
- Center
for Free Electron Laser Science, Max Planck
Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - Angel Rubio
- Center
for Free Electron Laser Science, Max Planck
Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
- Center
for Computational Quantum Physics, Simons
Foundation Flatiron Institute, New York, New York 10010 United States
- Nano-Bio
Spectroscopy Group, Departamento de Fisica de Materiales, Universidad del País Vasco, UPV/EHU- 20018 San Sebastián, Spain
| | - Dante M. Kennes
- Center
for Free Electron Laser Science, Max Planck
Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
- Institut
für Theorie der Statistischen Physik, RWTH Aachen University and JARA-Fundamentals of Future Information
Technology, 52056 Aachen, Germany
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27
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Liu E, Barré E, van Baren J, Wilson M, Taniguchi T, Watanabe K, Cui YT, Gabor NM, Heinz TF, Chang YC, Lui CH. Signatures of moiré trions in WSe 2/MoSe 2 heterobilayers. Nature 2021; 594:46-50. [PMID: 34079140 DOI: 10.1038/s41586-021-03541-z] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 04/12/2021] [Indexed: 02/05/2023]
Abstract
Moiré superlattices formed by van der Waals materials can support a wide range of electronic phases, including Mott insulators1-4, superconductors5-10 and generalized Wigner crystals2. When excitons are confined by a moiré superlattice, a new class of exciton emerges, which holds promise for realizing artificial excitonic crystals and quantum optical effects11-16. When such moiré excitons are coupled to charge carriers, correlated states may arise. However, no experimental evidence exists for charge-coupled moiré exciton states, nor have their properties been predicted by theory. Here we report the optical signatures of trions coupled to the moiré potential in tungsten diselenide/molybdenum diselenide heterobilayers. The moiré trions show multiple sharp emission lines with a complex charge-density dependence, in stark contrast to the behaviour of conventional trions. We infer distinct contributions to the trion emission from radiative decay in which the remaining carrier resides in different moiré minibands. Variation of the trion features is observed in different devices and sample areas, indicating high sensitivity to sample inhomogeneity and variability. The observation of these trion features motivates further theoretical and experimental studies of higher-order electron correlation effects in moiré superlattices.
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Affiliation(s)
- Erfu Liu
- Department of Physics and Astronomy, University of California, Riverside, CA, USA
| | - Elyse Barré
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA.,SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Jeremiah van Baren
- Department of Physics and Astronomy, University of California, Riverside, CA, USA
| | - Matthew Wilson
- Department of Physics and Astronomy, University of California, Riverside, CA, USA
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Ibaraki, Japan
| | - Kenji Watanabe
- National Institute for Materials Science (NIMS), Ibaraki, Japan
| | - Yong-Tao Cui
- Department of Physics and Astronomy, University of California, Riverside, CA, USA
| | - Nathaniel M Gabor
- Department of Physics and Astronomy, University of California, Riverside, CA, USA.,Canadian Institute for Advanced Research, Toronto, Ontario, Canada
| | - Tony F Heinz
- SLAC National Accelerator Laboratory, Menlo Park, CA, USA.,Department of Applied Physics, Stanford University, Stanford, CA, USA
| | - Yia-Chung Chang
- Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan.
| | - Chun Hung Lui
- Department of Physics and Astronomy, University of California, Riverside, CA, USA.
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28
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29
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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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30
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Yu J, Giridharagopal R, Li Y, Xie K, Li J, Cao T, Xu X, Ginger DS. Imaging Graphene Moiré Superlattices via Scanning Kelvin Probe Microscopy. NANO LETTERS 2021; 21:3280-3286. [PMID: 33749279 DOI: 10.1021/acs.nanolett.1c00609] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Moiré superlattices in van der Waals heterostructures are gaining increasing attention because they offer new opportunities to tailor and explore unique electronic phenomena. Using a combination of lateral piezoresponse force microscopy (LPFM) and scanning Kelvin probe microscopy (SKPM), we directly correlate ABAB and ABCA stacked graphene with local surface potential. We find that the surface potential of the ABCA domains is ∼15 mV higher (smaller work function) than that of the ABAB domains. First-principles calculations show that the different work functions between ABCA and ABAB domains arise from the stacking-dependent electronic structure. Moreover, while the moiré superlattice visualized by LPFM can change with time, imaging the surface potential distribution via SKPM appears more stable, enabling the mapping of ABAB and ABCA domains without tip-sample contact-induced effects. Our results provide a new means to visualize and probe local domain stacking in moiré superlattices along with its impact on electronic properties.
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Affiliation(s)
- Junxi Yu
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
- Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, and School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, Hunan, China
| | - Rajiv Giridharagopal
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Yuhao Li
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Kaichen Xie
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Jiangyu Li
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China
| | - Ting Cao
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Xiaodong Xu
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - David S Ginger
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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31
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Hesp NCH, Torre I, Barcons-Ruiz D, Herzig Sheinfux H, Watanabe K, Taniguchi T, Krishna Kumar R, Koppens FHL. Nano-imaging photoresponse in a moiré unit cell of minimally twisted bilayer graphene. Nat Commun 2021; 12:1640. [PMID: 33712606 PMCID: PMC7954806 DOI: 10.1038/s41467-021-21862-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 02/11/2021] [Indexed: 11/09/2022] Open
Abstract
Graphene-based moiré superlattices have recently emerged as a unique class of tuneable solid-state systems that exhibit significant optoelectronic activity. Local probing at length scales of the superlattice should provide deeper insight into the microscopic mechanisms of photoresponse and the exact role of the moiré lattice. Here, we employ a nanoscale probe to study photoresponse within a single moiré unit cell of minimally twisted bilayer graphene. Our measurements reveal a spatially rich photoresponse, whose sign and magnitude are governed by the fine structure of the moiré lattice and its orientation with respect to measurement contacts. This results in a strong directional effect and a striking spatial dependence of the gate-voltage response within the moiré domains. The spatial profile and carrier-density dependence of the measured photocurrent point towards a photo-thermoelectric induced response that is further corroborated by good agreement with numerical simulations. Our work shows sub-diffraction photocurrent spectroscopy is an exceptional tool for uncovering the optoelectronic properties of moiré superlattices.
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Affiliation(s)
- Niels C H Hesp
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Iacopo Torre
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - David Barcons-Ruiz
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Hanan Herzig Sheinfux
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki, Japan
| | - Roshan Krishna Kumar
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain.
| | - Frank H L Koppens
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain. .,ICREA-Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain.
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32
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Kerelsky A, Rubio-Verdú C, Xian L, Kennes DM, Halbertal D, Finney N, Song L, Turkel S, Wang L, Watanabe K, Taniguchi T, Hone J, Dean C, Basov DN, Rubio A, Pasupathy AN. Moiréless correlations in ABCA graphene. Proc Natl Acad Sci U S A 2021; 118:e2017366118. [PMID: 33468646 PMCID: PMC7848726 DOI: 10.1073/pnas.2017366118] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Atomically thin van der Waals materials stacked with an interlayer twist have proven to be an excellent platform toward achieving gate-tunable correlated phenomena linked to the formation of flat electronic bands. In this work we demonstrate the formation of emergent correlated phases in multilayer rhombohedral graphene--a simple material that also exhibits a flat electronic band edge but without the need of having a moiré superlattice induced by twisted van der Waals layers. We show that two layers of bilayer graphene that are twisted by an arbitrary tiny angle host large (micrometer-scale) regions of uniform rhombohedral four-layer (ABCA) graphene that can be independently studied. Scanning tunneling spectroscopy reveals that ABCA graphene hosts an unprecedentedly sharp van Hove singularity of 3-5-meV half-width. We demonstrate that when this van Hove singularity straddles the Fermi level, a correlated many-body gap emerges with peak-to-peak value of 9.5 meV at charge neutrality. Mean-field theoretical calculations for model with short-ranged interactions indicate that two primary candidates for the appearance of this broken symmetry state are a charge-transfer excitonic insulator and a ferrimagnet. Finally, we show that ABCA graphene hosts surface topological helical edge states at natural interfaces with ABAB graphene which can be turned on and off with gate voltage, implying that small-angle twisted double-bilayer graphene is an ideal programmable topological quantum material.
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Affiliation(s)
| | | | - Lede Xian
- Theory Department, Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
- Frontier Research Center, Songshan Lake Materials Laboratory, 523808 Dongguan, Guangdong, China
| | - Dante M Kennes
- Theory Department, Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
- Institut für Theorie der Statistischen Physik, Rheinisch-Westfälische Technische Hochschule Aachen University, 52056 Aachen, Germany
- Jülich Aachen Research Alliance-Fundamentals of Future Information Technology, 52056 Aachen, Germany
| | - Dorri Halbertal
- Department of Physics, Columbia University, New York, NY 10027
| | - Nathan Finney
- Department of Mechanical Engineering, Columbia University, New York, NY 10027
| | - Larry Song
- Department of Physics, Columbia University, New York, NY 10027
| | - Simon Turkel
- Department of Physics, Columbia University, New York, NY 10027
| | - Lei Wang
- Department of Physics, Columbia University, New York, NY 10027
| | - Kenji Watanabe
- National Institute for Materials Science, 1-1 Namiki, 305-0044 Tsukuba, Japan
| | - Takashi Taniguchi
- National Institute for Materials Science, 1-1 Namiki, 305-0044 Tsukuba, Japan
| | - James Hone
- Department of Mechanical Engineering, Columbia University, New York, NY 10027
| | - Cory Dean
- Department of Physics, Columbia University, New York, NY 10027
| | - Dmitri N Basov
- Department of Physics, Columbia University, New York, NY 10027
| | - Angel Rubio
- Theory Department, Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany;
- Center for Computational Quantum Physics, The Flatiron Institute, New York, NY 10010
- Nano-Bio Spectroscopy Group, Departamento de Fisica de Materiales, Universidad del País Vasco, 20018 San Sebastian, Spain
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