1
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Zeng Y, Crépel V, Millis AJ. Keldysh Field Theory of Dynamical Exciton Condensation Transitions in Nonequilibrium Electron-Hole Bilayers. PHYSICAL REVIEW LETTERS 2024; 132:266001. [PMID: 38996303 DOI: 10.1103/physrevlett.132.266001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 05/16/2024] [Accepted: 05/31/2024] [Indexed: 07/14/2024]
Abstract
Recent experiments have realized steady-state electrical injection of interlayer excitons in electron-hole bilayers subject to a large bias voltage. In the ideal case in which interlayer tunneling is negligibly weak, the system is in quasiequilibrium with a reduced effective band gap. Interlayer tunneling introduces a current and drives the system out of equilibrium. In this work we derive a nonequilibrium field theory description of interlayer excitons in biased electron-hole bilayers. In the large bias limit, we find that p-wave interlayer tunneling reduces the effective band gap and increases the effective temperature for intervalley excitons. We discuss possible experimental implications for InAs/GaSb quantum wells and transition metal dichalcogenide bilayers.
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Affiliation(s)
- Yongxin Zeng
- Department of Physics, Columbia University, New York, New York 10027, USA
- Center for Computational Quantum Physics, Flatiron Institute, New York, New York 10010, USA
- Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA
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2
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Li Q, Chen Y, Wei L, Chen H, Huang Y, Zhu Y, Zhu W, An D, Song J, Gan Q, Zhang Q, Watanabe K, Taniguchi T, Shi X, Novoselov KS, Wang R, Yu G, Wang L. Strongly coupled magneto-exciton condensates in large-angle twisted double bilayer graphene. Nat Commun 2024; 15:5065. [PMID: 38871728 DOI: 10.1038/s41467-024-49406-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 05/31/2024] [Indexed: 06/15/2024] Open
Abstract
Excitons, pairs of electrons and holes, undergo a Bose-Einstein condensation at low temperatures. An important platform to study excitons is double-layer two-dimensional electron gases, with two parallel planes of electrons and holes separated by a thin insulating layer. Lowering this separation (d) strengthens the exciton binding energy, however, leads to the undesired interlayer tunneling, resulting in annihilation of excitons. Here, we report the observation of a sequences of robust exciton condensates (ECs) in double bilayer graphene twisted to ~ 10° with no insulating mid-layer. The large momentum mismatch between two graphene layers suppresses interlayer tunneling, reaching a d ~ 0.334 nm. Measuring the bulk and edge transport, we find incompressible states corresponding to ECs when both layers are in half-filled N = 0, 1 Landau levels (LLs). Theoretical calculations suggest that the low-energy charged excitation of ECs can be meron-antimeron or particle-hole pair, which relies on both LL index and carrier type. Our results establish a novel platform with extreme coupling strength for studying quantum bosonic phase.
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Affiliation(s)
- Qingxin Li
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Yiwei Chen
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - LingNan Wei
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Hong Chen
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Yan Huang
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Yujian Zhu
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Wang Zhu
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Dongdong An
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Junwei Song
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Qikang Gan
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Qi Zhang
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Xiaoyang Shi
- Environmental and Sustainable Engineering, College of Engineering and Applied Science, University at Albany, Albany, NY, 12222, USA.
| | - Kostya S Novoselov
- Institute for Functional Intelligent Materials, National University of Singapore, Building S9, 4 Science Drive 2, Singapore, 117544, Singapore
| | - Rui Wang
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China.
| | - Geliang Yu
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China.
| | - Lei Wang
- National Laboratory of Solid-State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China.
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3
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Yuan Y, Liu L, Zhu J, Dong J, Chu Y, Wu F, Du L, Watanabe K, Taniguchi T, Shi D, Zhang G, Yang W. Interplay of Landau Quantization and Interminivalley Scatterings in a Weakly Coupled Moiré Superlattice. NANO LETTERS 2024; 24:6722-6729. [PMID: 38717299 PMCID: PMC11157648 DOI: 10.1021/acs.nanolett.4c01411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 05/02/2024] [Accepted: 05/02/2024] [Indexed: 06/06/2024]
Abstract
Double-layer quantum systems are promising platforms for realizing novel quantum phases. Here, we report a study of quantum oscillations (QOs) in a weakly coupled double-layer system composed of a large-angle twisted-double-bilayer graphene (TDBG). We quantify the interlayer coupling strength by measuring the interlayer capacitance from the QOs pattern at low temperatures, revealing electron-hole asymmetry. At high temperatures when SdHOs are thermally smeared, we observe resistance peaks when Landau levels (LLs) from two moiré minivalleys are aligned, regardless of carrier density; eventually, it results in a 2-fold increase of oscillating frequency in D, serving as compelling evidence of the magneto-intersub-band oscillations (MISOs) in double-layer systems. The temperature dependence of MISOs suggests that electron-electron interactions play a crucial role and the scattering times obtained from MISO thermal damping are correlated with the interlayer coupling strength. Our study reveals intriguing interplays among Landau quantization, moiré band structure, and scatterings.
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Affiliation(s)
- Yalong Yuan
- Beijing
National Laboratory for Condensed Matter Physics and Institute of
Physics, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
- School
of Physical Sciences, University of Chinese
Academy of Sciences, Beijing 100190, People’s
Republic of China
| | - Le Liu
- Beijing
National Laboratory for Condensed Matter Physics and Institute of
Physics, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
- School
of Physical Sciences, University of Chinese
Academy of Sciences, Beijing 100190, People’s
Republic of China
| | - Jundong Zhu
- Beijing
National Laboratory for Condensed Matter Physics and Institute of
Physics, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
- School
of Physical Sciences, University of Chinese
Academy of Sciences, Beijing 100190, People’s
Republic of China
| | - Jingwei Dong
- Beijing
National Laboratory for Condensed Matter Physics and Institute of
Physics, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
- School
of Physical Sciences, University of Chinese
Academy of Sciences, Beijing 100190, People’s
Republic of China
| | - Yanbang Chu
- Beijing
National Laboratory for Condensed Matter Physics and Institute of
Physics, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
- School
of Physical Sciences, University of Chinese
Academy of Sciences, Beijing 100190, People’s
Republic of China
| | - Fanfan Wu
- Beijing
National Laboratory for Condensed Matter Physics and Institute of
Physics, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
- School
of Physical Sciences, University of Chinese
Academy of Sciences, Beijing 100190, People’s
Republic of China
| | - Luojun Du
- Beijing
National Laboratory for Condensed Matter Physics and Institute of
Physics, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
- School
of Physical Sciences, University of Chinese
Academy of Sciences, Beijing 100190, People’s
Republic of China
| | - Kenji Watanabe
- Research
Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- Research
Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Dongxia Shi
- Beijing
National Laboratory for Condensed Matter Physics and Institute of
Physics, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
- School
of Physical Sciences, University of Chinese
Academy of Sciences, Beijing 100190, People’s
Republic of China
- Songshan
Lake Materials Laboratory, Dongguan 523808, People’s
Republic of China
| | - Guangyu Zhang
- Beijing
National Laboratory for Condensed Matter Physics and Institute of
Physics, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
- School
of Physical Sciences, University of Chinese
Academy of Sciences, Beijing 100190, People’s
Republic of China
- Songshan
Lake Materials Laboratory, Dongguan 523808, People’s
Republic of China
| | - Wei Yang
- Beijing
National Laboratory for Condensed Matter Physics and Institute of
Physics, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
- School
of Physical Sciences, University of Chinese
Academy of Sciences, Beijing 100190, People’s
Republic of China
- Songshan
Lake Materials Laboratory, Dongguan 523808, People’s
Republic of China
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Hoke JC, Li Y, May-Mann J, Watanabe K, Taniguchi T, Bradlyn B, Hughes TL, Feldman BE. Uncovering the spin ordering in magic-angle graphene via edge state equilibration. Nat Commun 2024; 15:4321. [PMID: 38773076 PMCID: PMC11109299 DOI: 10.1038/s41467-024-48385-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Accepted: 04/30/2024] [Indexed: 05/23/2024] Open
Abstract
The flat bands in magic-angle twisted bilayer graphene (MATBG) provide an especially rich arena to investigate interaction-driven ground states. While progress has been made in identifying the correlated insulators and their excitations at commensurate moiré filling factors, the spin-valley polarizations of the topological states that emerge at high magnetic field remain unknown. Here we introduce a technique based on twist-decoupled van der Waals layers that enables measurement of their electronic band structure and-by studying the backscattering between counter-propagating edge states-the determination of the relative spin polarization of their edge modes. We find that the symmetry-broken quantum Hall states that extend from the charge neutrality point in MATBG are spin unpolarized at even integer filling factors. The measurements also indicate that the correlated Chern insulator emerging from half filling of the flat valence band is spin unpolarized and suggest that its conduction band counterpart may be spin polarized.
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Affiliation(s)
- Jesse C Hoke
- Department of Physics, Stanford University, Stanford, CA, 94305, USA
- Geballe Laboratory for Advanced Materials, Stanford, CA, 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Yifan Li
- Department of Physics, Stanford University, Stanford, CA, 94305, USA
- Geballe Laboratory for Advanced Materials, Stanford, CA, 94305, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Julian May-Mann
- Department of Physics, Stanford University, Stanford, CA, 94305, USA
- Department of Physics and Institute for Condensed Matter Theory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Barry Bradlyn
- Department of Physics and Institute for Condensed Matter Theory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Taylor L Hughes
- Department of Physics and Institute for Condensed Matter Theory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Benjamin E Feldman
- Department of Physics, Stanford University, Stanford, CA, 94305, USA.
- Geballe Laboratory for Advanced Materials, Stanford, CA, 94305, USA.
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
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5
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Zhumagulov Y, Kochan D, Fabian J. Emergent Correlated Phases in Rhombohedral Trilayer Graphene Induced by Proximity Spin-Orbit and Exchange Coupling. PHYSICAL REVIEW LETTERS 2024; 132:186401. [PMID: 38759183 DOI: 10.1103/physrevlett.132.186401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 11/28/2023] [Accepted: 03/22/2024] [Indexed: 05/19/2024]
Abstract
The impact of proximity-induced spin-orbit and exchange coupling on the correlated phase diagram of rhombohedral trilayer graphene (RTG) is investigated theoretically. By employing ab initio-fitted effective models of RTG encapsulated by transition metal dichalcogenides (spin-orbit proximity effect) and ferromagnetic Cr_{2}Ge_{2}Te_{6} (exchange proximity effect), we incorporate the Coulomb interactions within the random-phase approximation to explore potential correlated phases at different displacement fields and doping. We find a rich spectrum of spin-valley resolved Stoner and intervalley coherence instabilities induced by the spin-orbit proximity effects, such as the emergence of a spin-valley-coherent phase due to the presence of valley-Zeeman coupling. Similarly, proximity exchange removes the phase degeneracies by biasing the spin direction, enabling a magnetocorrelation effect-strong sensitivity of the correlated phases to the relative magnetization orientations (parallel or antiparallel) of the encapsulating ferromagnetic layers.
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Affiliation(s)
- Yaroslav Zhumagulov
- Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
| | - Denis Kochan
- Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
- Institute of Physics, Slovak Academy of Sciences, 84511 Bratislava, Slovakia
- Center for Quantum Frontiers of Research and Technology (QFort), National Cheng Kung University, Tainan 70101, Taiwan
| | - Jaroslav Fabian
- Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
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6
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Kuang X, Pantaleón Peralta PA, Angel Silva-Guillén J, Yuan S, Guinea F, Zhan Z. Optical properties and plasmons in moiré structures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:173001. [PMID: 38232397 DOI: 10.1088/1361-648x/ad1f8c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 01/17/2024] [Indexed: 01/19/2024]
Abstract
The discoveries of numerous exciting phenomena in twisted bilayer graphene (TBG) are stimulating significant investigations on moiré structures that possess a tunable moiré potential. Optical response can provide insights into the electronic structures and transport phenomena of non-twisted and twisted moiré structures. In this article, we review both experimental and theoretical studies of optical properties such as optical conductivity, dielectric function, non-linear optical response, and plasmons in moiré structures composed of graphene, hexagonal boron nitride (hBN), and/or transition metal dichalcogenides. Firstly, a comprehensive introduction to the widely employed methodology on optical properties is presented. After, moiré potential induced optical conductivity and plasmons in non-twisted structures are reviewed, such as single layer graphene-hBN, bilayer graphene-hBN and graphene-metal moiré heterostructures. Next, recent investigations of twist-angle dependent optical response and plasmons are addressed in twisted moiré structures. Additionally, we discuss how optical properties and plasmons could contribute to the understanding of the many-body effects and superconductivity observed in moiré structures.
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Affiliation(s)
- Xueheng Kuang
- Yangtze Delta Industrial Innovation Center of Quantum Science and Technology, Suzhou 215000, People's Republic of China
| | | | - Jose Angel Silva-Guillén
- Instituto Madrileño de Estudios Avanzados, IMDEA Nanociencia, Calle Faraday 9, 28049 Madrid, Spain
| | - Shengjun Yuan
- Key Laboratory of Artificial Micro- and Nano-structures of the Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
- Wuhan Institute of Quantum Technology, Wuhan 430206, People's Republic of China
| | - Francisco Guinea
- Instituto Madrileño de Estudios Avanzados, IMDEA Nanociencia, Calle Faraday 9, 28049 Madrid, Spain
- Donostia International Physics Center, Paseo Manuel de Lardizábal 4, 20018 San Sebastián, Spain
| | - Zhen Zhan
- Instituto Madrileño de Estudios Avanzados, IMDEA Nanociencia, Calle Faraday 9, 28049 Madrid, Spain
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7
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He M, Cai J, Zhang YH, Liu Y, Li Y, Taniguchi T, Watanabe K, Cobden DH, Yankowitz M, Xu X. Symmetry-Broken Chern Insulators in Twisted Double Bilayer Graphene. NANO LETTERS 2023. [PMID: 37983529 DOI: 10.1021/acs.nanolett.3c03414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Twisted double bilayer graphene (tDBG) has emerged as a rich platform for studying strongly correlated and topological states, as its flat bands can be continuously tuned by both a perpendicular displacement field and a twist angle. Here, we construct a phase diagram representing the correlated and topological states as a function of these parameters, based on measurements of over a dozen tDBG devices encompassing two distinct stacking configurations. We find a hierarchy of symmetry-broken states that emerge sequentially as the twist angle approaches an apparent optimal value of θ ≈ 1.34°. Nearby this angle, we discover a symmetry-broken Chern insulator (SBCI) state associated with a band filling of 7/2 as well as an incipient SBCI state associated with 11/3 filling. We further observe an anomalous Hall effect at zero field in all samples supporting SBCI states, indicating spontaneous time-reversal symmetry breaking and possible moiré unit cell enlargement at zero magnetic field.
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Affiliation(s)
- Minhao He
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Jiaqi Cai
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Ya-Hui Zhang
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Yang Liu
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Yuhao Li
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - 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
| | - David H Cobden
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Matthew Yankowitz
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
- 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
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, United States
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8
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Slot MR, Maximenko Y, Haney PM, Kim S, Walkup DT, Strelcov E, Le ST, Shih EM, Yildiz D, Blankenship SR, Watanabe K, Taniguchi T, Barlas Y, Zhitenev NB, Ghahari F, Stroscio JA. A quantum ruler for orbital magnetism in moiré quantum matter. Science 2023; 382:81-87. [PMID: 37797004 DOI: 10.1126/science.adf2040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 08/30/2023] [Indexed: 10/07/2023]
Abstract
For almost a century, magnetic oscillations have been a powerful "quantum ruler" for measuring Fermi surface topology. In this study, we used Landau-level spectroscopy to unravel the energy-resolved valley-contrasting orbital magnetism and large orbital magnetic susceptibility that contribute to the energies of Landau levels of twisted double-bilayer graphene. These orbital magnetism effects led to substantial deviations from the standard Onsager relation, which manifested as a breakdown in scaling of Landau-level orbits. These substantial magnetic responses emerged from the nontrivial quantum geometry of the electronic structure and the large length scale of the moiré lattice potential. Going beyond traditional measurements, Landau-level spectroscopy performed with a scanning tunneling microscope offers a complete quantum ruler that resolves the full energy dependence of orbital magnetic properties in moiré quantum matter.
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Affiliation(s)
- M R Slot
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Department of Physics, Georgetown University, Washington, DC 20007, USA
| | - Y Maximenko
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - P M Haney
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - S Kim
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Joint Quantum Institute, Department of Physics, University of Maryland, College Park, MD 20742, USA
| | - D T Walkup
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - E Strelcov
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - Son T Le
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - E M Shih
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - D Yildiz
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Joint Quantum Institute, Department of Physics, University of Maryland, College Park, MD 20742, USA
| | - S R Blankenship
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - K Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - T Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Y Barlas
- Department of Physics, University of Nevada, Reno, NV 89557, USA
| | - N B Zhitenev
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - F Ghahari
- Department of Physics and Astronomy, George Mason University, Fairfax, VA 22030, USA
| | - J A Stroscio
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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9
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Kim S, Kim D, Watanabe K, Taniguchi T, Smet JH, Kim Y. Orbitally Controlled Quantum Hall States in Decoupled Two-Bilayer Graphene Sheets. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2300574. [PMID: 37259684 PMCID: PMC10427396 DOI: 10.1002/advs.202300574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 04/29/2023] [Indexed: 06/02/2023]
Abstract
The authors report on integer and fractional quantum Hall states in a stack of two twisted Bernal bilayer graphene sheets. By exploiting the momentum mismatch in reciprocal space, the single-particle tunneling between both bilayers is suppressed. Since the bilayers are spatially separated by only 0.34 nm, the stack benefits from strong interlayer Coulombic interactions. These interactions can cause the formation of a Bose-Einstein condensate. Indeed, such a condensate is observed for half-filling in each bilayer sheet. However, only when the partially filled levels have orbital index 1. It is absent for partially filled levels with orbital index 0. This discrepancy is tentatively attributed to the role of skyrmion/anti-skyrmion pair excitations and the dependence of the energy of these excitations on the orbital index. The application of asymmetric top and bottom gate voltages enables to influence the orbital nature of the electronic states of the graphene bilayers at the chemical potential and to navigate in orbital mixed space. The latter hosts an even denominator fractional quantum Hall state at total filling of -3/2. These observations suggest a unique edge reconstruction involving both electrons and chiral p-wave composite fermions.
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Affiliation(s)
- Soyun Kim
- Department of Physics and ChemistryDaegu Gyeongbuk Institute of Science and Technology (DGIST)Daegu42988Republic of Korea
| | - Dohun Kim
- Department of Physics and ChemistryDaegu Gyeongbuk Institute of Science and Technology (DGIST)Daegu42988Republic of Korea
| | - Kenji Watanabe
- Research Center for Functional MaterialsNational Institute for Materials ScienceTsukuba305‐0044Japan
| | - Takashi Taniguchi
- International Center for Materials NanoarchitectonicsNational Institute for Materials ScienceTsukuba305‐0044Japan
| | - Jurgen H. Smet
- Max Planck Institute for Solid State Research70569StuttgartGermany
| | - Youngwook Kim
- Department of Physics and ChemistryDaegu Gyeongbuk Institute of Science and Technology (DGIST)Daegu42988Republic of Korea
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10
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Li Q, Liu T, Li Y, Li F, Zhao Y, Huang S. A Wrinkling and Etching-Assisted Regrowth Strategy for Large-Area Bilayer Graphene Preparation on Cu. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2059. [PMID: 37513070 PMCID: PMC10385747 DOI: 10.3390/nano13142059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 07/05/2023] [Accepted: 07/10/2023] [Indexed: 07/30/2023]
Abstract
Bilayer graphene is a contender of interest for functional electronic applications because of its variable band gap due to interlayer interactions. Graphene growth on Cu is self-limiting, thus despite the fact that chemical vapor deposition (CVD) has made substantial strides in the production of monolayer and single-crystal graphene on Cu substrates, the direct synthesizing of high-quality, large-area bilayer graphene remains an enormous challenge. In order to tackle this issue, we present a simple technique using typical CVD graphene growth followed by a repetitive wrinkling-etching-regrowth procedure. The key element of our approach is the rapid cooling process that causes high-density wrinkles to form in the monolayer area rather than the bilayer area. Next, wrinkled sites are selectively etched with hydrogen, exposing a significant portion of the active Cu surface, and leaving the remaining bilayer areas, which enhance the nucleation and growth of the second graphene layer. A fully covered graphene with 78 ± 2.8% bilayer coverage and a bilayer transmittance of 95.6% at room temperature can be achieved by modifying the process settings. Bilayer graphene samples are examined using optical microscopy (OM), scanning electron microscopy (SEM), Raman spectroscopy, and an atomic force microscope (AFM) during this process. The outcomes of our research are beneficial in clarifying the growth processes and future commercial applications of bilayer graphene.
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Affiliation(s)
- Qiongyu Li
- School of Electronic, Electrical Engineering and Physics, Fujian University of Technology, Fuzhou 350118, China
| | - Tongzhi Liu
- School of Electronic, Electrical Engineering and Physics, Fujian University of Technology, Fuzhou 350118, China
| | - You Li
- MIIT Key Laboratory of Semiconductor Microstructure and Quantum Sensing, Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Fang Li
- MIIT Key Laboratory of Semiconductor Microstructure and Quantum Sensing, Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Yanshuai Zhao
- School of Electronic, Electrical Engineering and Physics, Fujian University of Technology, Fuzhou 350118, China
| | - Shihao Huang
- School of Electronic, Electrical Engineering and Physics, Fujian University of Technology, Fuzhou 350118, China
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11
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Yang K, Gao X, Wang Y, Zhang T, Gao Y, Lu X, Zhang S, Liu J, Gu P, Luo Z, Zheng R, Cao S, Wang H, Sun X, Watanabe K, Taniguchi T, Li X, Zhang J, Dai X, Chen JH, Ye Y, Han Z. Unconventional correlated insulator in CrOCl-interfaced Bernal bilayer graphene. Nat Commun 2023; 14:2136. [PMID: 37059725 PMCID: PMC10104821 DOI: 10.1038/s41467-023-37769-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 03/30/2023] [Indexed: 04/16/2023] Open
Abstract
The realization of graphene gapped states with large on/off ratios over wide doping ranges remains challenging. Here, we investigate heterostructures based on Bernal-stacked bilayer graphene (BLG) atop few-layered CrOCl, exhibiting an over-1-GΩ-resistance insulating state in a widely accessible gate voltage range. The insulating state could be switched into a metallic state with an on/off ratio up to 107 by applying an in-plane electric field, heating, or gating. We tentatively associate the observed behavior to the formation of a surface state in CrOCl under vertical electric fields, promoting electron-electron (e-e) interactions in BLG via long-range Coulomb coupling. Consequently, at the charge neutrality point, a crossover from single particle insulating behavior to an unconventional correlated insulator is enabled, below an onset temperature. We demonstrate the application of the insulating state for the realization of a logic inverter operating at low temperatures. Our findings pave the way for future engineering of quantum electronic states based on interfacial charge coupling.
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Affiliation(s)
- Kaining Yang
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan, PR China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, PR China
| | - Xiang Gao
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan, PR China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, PR China
| | - Yaning Wang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China
- School of Material Science and Engineering, University of Science and Technology of China, Anhui, China
| | - Tongyao Zhang
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan, PR China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, PR China
| | - Yuchen Gao
- Collaborative Innovation Center of Quantum Matter, Beijing, China
- State Key Lab for Mesoscopic Physics and Frontiers Science Center for Nano-Optoelectronics, School of Physics, Peking University, Beijing, China
| | - Xin Lu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, China.
| | - Shihao Zhang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, China
| | - Jianpeng Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai, China
| | - Pingfan Gu
- Collaborative Innovation Center of Quantum Matter, Beijing, China
- State Key Lab for Mesoscopic Physics and Frontiers Science Center for Nano-Optoelectronics, School of Physics, Peking University, Beijing, China
| | - Zhaoping Luo
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China
| | - Runjie Zheng
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China
| | - Shimin Cao
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China
- Beijing Academy of Quantum Information Sciences, Beijing, China
| | - Hanwen Wang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China
| | - Xingdan Sun
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Xiuyan Li
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China
| | - Jing Zhang
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan, PR China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, PR China
| | - Xi Dai
- Materials Department, University of California, Santa Barbara, CA, USA.
- Department of Physics, The Hongkong University of Science and Technology, Hong Kong, China.
| | - Jian-Hao Chen
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China.
- Beijing Academy of Quantum Information Sciences, Beijing, China.
- Key Laboratory for the Physics and Chemistry of Nanodevices, Peking University, Beijing, China.
- Hefei National Laboratory, Hefei, China.
| | - Yu Ye
- Collaborative Innovation Center of Quantum Matter, Beijing, China.
- State Key Lab for Mesoscopic Physics and Frontiers Science Center for Nano-Optoelectronics, School of Physics, Peking University, Beijing, China.
| | - Zheng Han
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan, PR China.
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, PR China.
- Liaoning Academy of Materials, Shenyang, China.
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12
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Aggarwal D, Narula R, Ghosh S. A primer on twistronics: a massless Dirac fermion's journey to moiré patterns and flat bands in twisted bilayer graphene. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:143001. [PMID: 36745922 DOI: 10.1088/1361-648x/acb984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 02/06/2023] [Indexed: 06/18/2023]
Abstract
The recent discovery of superconductivity in magic-angle twisted bilayer graphene (TBLG) has sparked a renewed interest in the strongly-correlated physics ofsp2carbons, in stark contrast to preliminary investigations which were dominated by the one-body physics of the massless Dirac fermions. We thus provide a self-contained, theoretical perspective of the journey of graphene from its single-particle physics-dominated regime to the strongly-correlated physics of the flat bands. Beginning from the origin of the Dirac points in condensed matter systems, we discuss the effect of the superlattice on the Fermi velocity and Van Hove singularities in graphene and how it leads naturally to investigations of the moiré pattern in van der Waals heterostructures exemplified by graphene-hexagonal boron-nitride and TBLG. Subsequently, we illuminate the origin of flat bands in TBLG at the magic angles by elaborating on a broad range of prominent theoretical works in a pedagogical way while linking them to available experimental support, where appropriate. We conclude by providing a list of topics in the study of the electronic properties of TBLG not covered by this review but may readily be approached with the help of this primer.
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Affiliation(s)
| | - Rohit Narula
- Department of Physics, IIT Delhi, Hauz Khas, New Delhi, India
| | - Sankalpa Ghosh
- Department of Physics, IIT Delhi, Hauz Khas, New Delhi, India
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13
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Facile Fabrication of a Bio-Inspired Leaf Vein-Based Ultra-Sensitive Humidity Sensor with a Hygroscopic Polymer. Polymers (Basel) 2022; 14:polym14225030. [PMID: 36433157 PMCID: PMC9695871 DOI: 10.3390/polym14225030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 11/15/2022] [Accepted: 11/16/2022] [Indexed: 11/22/2022] Open
Abstract
Bio-inspired materials have received significant interest in the development of flexible electronics due to their natural grid structures, especially natural leaf vein networks. In this work, a bio-inspired leaf vein-based flexible humidity sensor is demonstrated. The proposed sensor is composed of a leaf/Al/glycerin/Ag paste. The Al-deposited leaf vein networks are used as a bottom electrode with a resistance of around 100 Ω. The humidity sensor responds well to relative humidity (RH) levels ranging from 15% to 70% at room temperature. The fabricated humidity sensor exhibits an ultra-sensitive response to different humidity conditions due to the biodegradable insulating hygroscopic polymer (glycerin), specifically the ionic conductivity reaction. To further verify the presence of ionic conduction, the device performance is tested by doping NaCl salt into the hygroscopic polymer sensing layer. In addition, both the repeatability and flexibility of the sensor are tested under different bending angles (0°, 90°, 180°, and 360°). The bioinspired ultrasensitive humidity sensor with a biocompatible and biodegradable sensing layer holds great potential, especially for health care applications (e.g., respiratory monitoring) without causing any body harm.
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14
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Bandurin DA, Principi A, Phinney IY, Taniguchi T, Watanabe K, Jarillo-Herrero P. Interlayer Electron-Hole Friction in Tunable Twisted Bilayer Graphene Semimetal. PHYSICAL REVIEW LETTERS 2022; 129:206802. [PMID: 36461999 DOI: 10.1103/physrevlett.129.206802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Revised: 08/22/2022] [Accepted: 10/21/2022] [Indexed: 06/17/2023]
Abstract
Charge-neutral conducting systems represent a class of materials with unusual properties governed by electron-hole (e-h) interactions. Depending on the quasiparticle statistics, band structure, and device geometry these semimetallic phases of matter can feature unconventional responses to external fields that often defy simple interpretations in terms of single-particle physics. Here we show that small-angle twisted bilayer graphene (SA TBG) offers a highly tunable system in which to explore interactions-limited electron conduction. By employing a dual-gated device architecture we tune our devices from a nondegenerate charge-neutral Dirac fluid to a compensated two-component e-h Fermi liquid where spatially separated electrons and holes experience strong mutual friction. This friction is revealed through the T^{2} resistivity that accurately follows the e-h drag theory we develop. Our results provide a textbook illustration of a smooth transition between different interaction-limited transport regimes and clarify the conduction mechanisms in charge-neutral SA TBG.
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Affiliation(s)
- D A Bandurin
- Department of Materials Science and Engineering, National University of Singapore, 117575 Singapore
| | - A Principi
- School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom
| | - I Y Phinney
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - T Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute of Material Science, Tsukuba 305-0044, Japan
| | - K Watanabe
- Research Center for Functional Materials, National Institute of Material Science, Tsukuba 305-0044, Japan
| | - P Jarillo-Herrero
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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15
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Spontaneous time-reversal symmetry breaking in twisted double bilayer graphene. Nat Commun 2022; 13:6468. [PMID: 36309518 PMCID: PMC9617879 DOI: 10.1038/s41467-022-34192-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 10/12/2022] [Indexed: 11/08/2022] Open
Abstract
Twisted double bilayer graphene (tDBG) comprises two Bernal-stacked bilayer graphene sheets with a twist between them. Gate voltages applied to top and back gates of a tDBG device tune both the flatness and topology of the electronic bands, enabling an unusual level of experimental control. Metallic states with broken spin and valley symmetries have been observed in tDBG devices with twist angles in the range 1.2–1.3°, but the topologies and order parameters of these states have remained unclear. We report the observation of an anomalous Hall effect in the correlated metal state of tDBG, with hysteresis loops spanning hundreds of mT in out-of-plane magnetic field (B⊥) that demonstrate spontaneously broken time-reversal symmetry. The B⊥ hysteresis persists for in-plane fields up to several Tesla, suggesting valley (orbital) ferromagnetism. At the same time, the resistivity is strongly affected by even mT-scale values of in-plane magnetic field, pointing to spin-valley coupling or to a direct orbital coupling between in-plane field and the valley degree of freedom. Twisted double bilayer graphene (tDBG) comprises two Bernal-stacked bilayer graphene sheets with a twist between them. Here, the authors report a strong anomalous Hall effect in the correlated-metal regime of tDBG, indicating time reversal symmetry breaking from orbital ferromagnetism, likely associated with valley polarization.
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16
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Lin ML, Feng M, Wu JB, Ran FR, Chen T, Luo WX, Wu H, Han WP, Zhang X, Liu XL, Xu Y, Li H, Wang YF, Tan PH. Intralayer Phonons in Multilayer Graphene Moiré Superlattices. Research (Wash D C) 2022; 2022:9819373. [PMID: 35707049 PMCID: PMC9175117 DOI: 10.34133/2022/9819373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 04/08/2022] [Indexed: 11/16/2022] Open
Abstract
Moiré pattern in twisted multilayers (tMLs) induces many emergent phenomena by subtle variation of atomic registry to modulate quasiparticles and their interactions, such as superconductivity, moiré excitons, and moiré phonons. The periodic superlattice potential introduced by moiré pattern also underlies patterned interlayer coupling at the interface of tMLs. Although this arising patterned interfacial coupling is much weaker than in-plane atomic interactions, it is crucial in moiré systems, as captured by the renormalized interlayer phonons in twisted bilayer transitional metal dichalcogenides. Here, we determine the quantitative relationship between the lattice dynamics of intralayer out-of-plane optical (ZO) phonons and patterned interfacial coupling in multilayer graphene moiré superlattices (MLG-MS) by the proposed perturbation model, which is previously challenging for MLGs due to their out-of-phase displacements of adjacent atoms in one atomic plane. We unveil that patterned interfacial coupling introduces profound modulations on Davydov components of nonfolded ZO phonon that are localized within the AB-stacked constituents, while the coupling results in layer-extended vibrations with symmetry of moiré pattern for moiré ZO phonons. Our work brings further degrees of freedom to engineer moiré physics according to the modulations imprinted on the phonon frequency and wavefunction.
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Affiliation(s)
- Miao-Ling Lin
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering & CAS Center of Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Min Feng
- School of Physics, Nankai University, Tianjin 300071, China
| | - Jiang-Bin Wu
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Fei-Rong Ran
- Key Laboratory of Flexible Electronics and Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China
| | - Tao Chen
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Wei-Xia Luo
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering & CAS Center of Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Heng Wu
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering & CAS Center of Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wen-Peng Han
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Xin Zhang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Xue-Lu Liu
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Yang Xu
- School of Micro-nanoelectronics, State Key Laboratory of Silicon Materials, Hangzhou Global Scientific and Technological Innovation Center, ZJU-UIUC Joint Institute, Zhejiang University, Hangzhou 310027, China
| | - Hai Li
- Key Laboratory of Flexible Electronics and Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China
| | - Yu-Fang Wang
- School of Physics, Nankai University, Tianjin 300071, China
| | - Ping-Heng Tan
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering & CAS Center of Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China
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17
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Sager LM, Schouten AO, Mazziotti DA. Beginnings of exciton condensation in coronene analog of graphene double layer. J Chem Phys 2022; 156:154702. [PMID: 35459326 DOI: 10.1063/5.0084564] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Exciton condensation, a Bose-Einstein condensation of excitons into a single quantum state, has recently been achieved in low-dimensional materials including twin layers of graphene and van der Waals heterostructures. Here, we computationally examine the beginnings of exciton condensation in a double layer composed of coronene, a seven-benzene-ring patch of graphene. As a function of interlayer separation, we compute the exciton population in a single coherent quantum state, showing that the population peaks around 1.8 at distances near 2 Å. Visualization reveals interlayer excitons at the separation distance of the condensate. We determine the exciton population as a function of the twist angle between two coronene layers to reveal the magic angles at which the condensation peaks. As with previous recent calculations showing some exciton condensation in hexacene double layers and benzene stacks, the present two-electron reduced-density-matrix calculations with coronene provide computational evidence for the ability to realize exciton condensation in molecular-scale analogs of extended systems such as the graphene double layer.
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Affiliation(s)
- LeeAnn M Sager
- Department of Chemistry and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
| | - Anna O Schouten
- Department of Chemistry and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
| | - David A Mazziotti
- Department of Chemistry and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
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18
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Zhang Q, Xiao X, Li L, Geng D, Chen W, Hu W. Additive-Assisted Growth of Scaled and Quality 2D Materials. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2107241. [PMID: 35092150 DOI: 10.1002/smll.202107241] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 12/19/2021] [Indexed: 06/14/2023]
Abstract
2D materials are increasingly becoming key components in modern electronics because of their prominent electronic and optoelectronic properties. The central and premise to the entire discipline of 2D materials lie in the high-quality and scaled preparations. The chemical vapor deposition (CVD) method offers compelling benefits in terms of scalability and controllability in shaping large-area and high-quality 2D materials. The past few years have witnessed development of numerous CVD growth strategies, with the use of additives attracting substantial attention in the production of scaled 2D crystals. This review provides an overview of different additives used in CVD growth of 2D materials, as well as a methodical demonstration of their vital roles. In addition, the intrinsic mechanisms of the production of scaled 2D crystals with additives are also discussed. Lastly, reliable guidance on the future design of optimal CVD synthesis routes is provided by analyzing the accessibility, pricing, by-products, controllability, universality, and commercialization of various additives.
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Affiliation(s)
- Qing Zhang
- Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Fuzhou, 350207, China
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
| | - Xixi Xiao
- Department of Chemistry, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, 300072, China
| | - Lin Li
- Institute of Molecular Plus, Tianjin University, Tianjin, 300072, China
| | - Dechao Geng
- Department of Chemistry, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, 300072, China
| | - Wei Chen
- Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Fuzhou, 350207, China
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
| | - Wenping Hu
- Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Fuzhou, 350207, China
- Department of Chemistry, Tianjin University & Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, 300072, China
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19
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Pham PV, Bodepudi SC, Shehzad K, Liu Y, Xu Y, Yu B, Duan X. 2D Heterostructures for Ubiquitous Electronics and Optoelectronics: Principles, Opportunities, and Challenges. Chem Rev 2022; 122:6514-6613. [PMID: 35133801 DOI: 10.1021/acs.chemrev.1c00735] [Citation(s) in RCA: 89] [Impact Index Per Article: 44.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A grand family of two-dimensional (2D) materials and their heterostructures have been discovered through the extensive experimental and theoretical efforts of chemists, material scientists, physicists, and technologists. These pioneering works contribute to realizing the fundamental platforms to explore and analyze new physical/chemical properties and technological phenomena at the micro-nano-pico scales. Engineering 2D van der Waals (vdW) materials and their heterostructures via chemical and physical methods with a suitable choice of stacking order, thickness, and interlayer interactions enable exotic carrier dynamics, showing potential in high-frequency electronics, broadband optoelectronics, low-power neuromorphic computing, and ubiquitous electronics. This comprehensive review addresses recent advances in terms of representative 2D materials, the general fabrication methods, and characterization techniques and the vital role of the physical parameters affecting the quality of 2D heterostructures. The main emphasis is on 2D heterostructures and 3D-bulk (3D) hybrid systems exhibiting intrinsic quantum mechanical responses in the optical, valley, and topological states. Finally, we discuss the universality of 2D heterostructures with representative applications and trends for future electronics and optoelectronics (FEO) under the challenges and opportunities from physical, nanotechnological, and material synthesis perspectives.
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Affiliation(s)
- Phuong V Pham
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Center (HIC), Zhejiang University, Xiaoshan 311200, China.,State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, China.,ZJU-UIUC Joint Institute, Zhejiang University, Jiaxing 314400, China
| | - Srikrishna Chanakya Bodepudi
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Center (HIC), Zhejiang University, Xiaoshan 311200, China.,State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, China.,ZJU-UIUC Joint Institute, Zhejiang University, Jiaxing 314400, China
| | - Khurram Shehzad
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Center (HIC), Zhejiang University, Xiaoshan 311200, China.,State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, China.,ZJU-UIUC Joint Institute, Zhejiang University, Jiaxing 314400, China
| | - Yuan Liu
- School of Physics and Electronics, Hunan University, Hunan 410082, China
| | - Yang Xu
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Center (HIC), Zhejiang University, Xiaoshan 311200, China.,State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, China.,ZJU-UIUC Joint Institute, Zhejiang University, Jiaxing 314400, China
| | - Bin Yu
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Center (HIC), Zhejiang University, Xiaoshan 311200, China.,State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, China.,ZJU-UIUC Joint Institute, Zhejiang University, Jiaxing 314400, China
| | - Xiangfeng Duan
- Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, California 90095-1569, United States
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20
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Tomić P, Rickhaus P, Garcia-Ruiz A, Zheng G, Portolés E, Fal'ko V, Watanabe K, Taniguchi T, Ensslin K, Ihn T, de Vries FK. Scattering between Minivalleys in Twisted Double Bilayer Graphene. PHYSICAL REVIEW LETTERS 2022; 128:057702. [PMID: 35179933 DOI: 10.1103/physrevlett.128.057702] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 11/29/2021] [Accepted: 12/08/2021] [Indexed: 06/14/2023]
Abstract
A unique feature of the complex band structures of moiré materials is the presence of minivalleys, their hybridization, and scattering between them. Here, we investigate magnetotransport oscillations caused by scattering between minivalleys-a phenomenon analogous to magnetointersubband oscillations-in a twisted double bilayer graphene sample with a twist angle of 1.94°. We study and discuss the potential scattering mechanisms and find an electron-phonon mechanism and valley conserving scattering to be likely. Finally, we discuss the relevance of our findings for different materials and twist angles.
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Affiliation(s)
- Petar Tomić
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Peter Rickhaus
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Aitor Garcia-Ruiz
- National Graphene Institute, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Giulia Zheng
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Elías Portolés
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Vladimir Fal'ko
- National Graphene Institute, University of Manchester, Manchester M13 9PL, United Kingdom
- Henry Royce Institute for Advanced Materials, M13 9PL Manchester, United Kingdom
| | - 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
| | - Klaus Ensslin
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
- Quantum Center, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Thomas Ihn
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
- Quantum Center, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Folkert K de Vries
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
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21
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Hao T, Hao T. Quantized conductance and superconductivity of twisted graphene and other 2D crystals explained with the Eyring’s rate process theory and free volume concept. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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22
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Fan Q, Miao J, Liu X, Zuo X, Zhang W, Tian M, Zhu S, Qu L, Zhang X. Biomimetic Hierarchically Silver Nanowire Interwoven MXene Mesh for Flexible Transparent Electrodes and Invisible Camouflage Electronics. NANO LETTERS 2022; 22:740-750. [PMID: 35019663 DOI: 10.1021/acs.nanolett.1c04185] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Flexible transparent electrodes demand high transparency, low sheet resistance, as well as excellent mechanical flexibility simultaneously, however they still remain to be a great challenge due to"trade-off" effect. Herein, inspired by a hollow interconnected leaf vein, we developed robust transparent conductive mesh with biomimetic interwoven structure via hierarchically self-assembles silver nanowires interwoven metal carbide/nitride (MXene) sheets along directional microfibers. Strong interfacial interactions between plant fibers and conductive units facilitate hierarchically interwoven conductive mesh constructed orderly on flexible and lightweight veins while maintaining high transparency, effectively avoiding the trade-off effect between optoelectronic properties. The flexible transparent electrodes exhibit sheet resistance of 0.5 Ω sq-1 and transparency of 81.6%, with a remarkably high figure of merit of 3523. In addition, invisible camouflage sensors are further successfully developed as a proof of concept that could monitor human body motion signals in an imperceptible state. The flexible transparent conductive mesh holds great potential in high-performance wearable optoelectronics and camouflage electronics.
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Affiliation(s)
- Qiang Fan
- Research Center for Intelligent and Wearable Technology, College of Textiles and Clothing, State Key Laboratory of Bio-Fibers and Eco-Textiles, Collaborative Innovation Center for Eco-Textiles of Shandong Province, Qingdao University, Qingdao, Shandong 266071, P.R. China
| | - Jinlei Miao
- Research Center for Intelligent and Wearable Technology, College of Textiles and Clothing, State Key Laboratory of Bio-Fibers and Eco-Textiles, Collaborative Innovation Center for Eco-Textiles of Shandong Province, Qingdao University, Qingdao, Shandong 266071, P.R. China
| | - Xuhua Liu
- Research Center for Intelligent and Wearable Technology, College of Textiles and Clothing, State Key Laboratory of Bio-Fibers and Eco-Textiles, Collaborative Innovation Center for Eco-Textiles of Shandong Province, Qingdao University, Qingdao, Shandong 266071, P.R. China
| | - Xingwei Zuo
- Research Center for Intelligent and Wearable Technology, College of Textiles and Clothing, State Key Laboratory of Bio-Fibers and Eco-Textiles, Collaborative Innovation Center for Eco-Textiles of Shandong Province, Qingdao University, Qingdao, Shandong 266071, P.R. China
| | - Wenxiao Zhang
- Research Center for Intelligent and Wearable Technology, College of Textiles and Clothing, State Key Laboratory of Bio-Fibers and Eco-Textiles, Collaborative Innovation Center for Eco-Textiles of Shandong Province, Qingdao University, Qingdao, Shandong 266071, P.R. China
| | - Mingwei Tian
- Research Center for Intelligent and Wearable Technology, College of Textiles and Clothing, State Key Laboratory of Bio-Fibers and Eco-Textiles, Collaborative Innovation Center for Eco-Textiles of Shandong Province, Qingdao University, Qingdao, Shandong 266071, P.R. China
| | - Shifeng Zhu
- Research Center for Intelligent and Wearable Technology, College of Textiles and Clothing, State Key Laboratory of Bio-Fibers and Eco-Textiles, Collaborative Innovation Center for Eco-Textiles of Shandong Province, Qingdao University, Qingdao, Shandong 266071, P.R. China
| | - Lijun Qu
- Research Center for Intelligent and Wearable Technology, College of Textiles and Clothing, State Key Laboratory of Bio-Fibers and Eco-Textiles, Collaborative Innovation Center for Eco-Textiles of Shandong Province, Qingdao University, Qingdao, Shandong 266071, P.R. China
| | - Xueji Zhang
- Research Center for Intelligent and Wearable Technology, College of Textiles and Clothing, State Key Laboratory of Bio-Fibers and Eco-Textiles, Collaborative Innovation Center for Eco-Textiles of Shandong Province, Qingdao University, Qingdao, Shandong 266071, P.R. China
- School of Biomedical Engineering, Shenzhen University Health Science Center, Shenzhen, Guangdong 518060, P.R. China
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23
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A compact device sustains a fluid of bosons. Nature 2021. [DOI: 10.1038/d41586-021-02876-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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24
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Szentpéteri B, Rickhaus P, de Vries FK, Márffy A, Fülöp B, Tóvári E, Watanabe K, Taniguchi T, Kormányos A, Csonka S, Makk P. Tailoring the Band Structure of Twisted Double Bilayer Graphene with Pressure. NANO LETTERS 2021; 21:8777-8784. [PMID: 34662136 PMCID: PMC8554798 DOI: 10.1021/acs.nanolett.1c03066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 10/11/2021] [Indexed: 05/21/2023]
Abstract
Twisted two-dimensional structures open new possibilities in band structure engineering. At magic twist angles, flat bands emerge, which gave a new drive to the field of strongly correlated physics. In twisted double bilayer graphene dual gating allows changing of the Fermi level and hence the electron density and also allows tuning of the interlayer potential, giving further control over band gaps. Here, we demonstrate that by application of hydrostatic pressure, an additional control of the band structure becomes possible due to the change of tunnel couplings between the layers. We find that the flat bands and the gaps separating them can be drastically changed by pressures up to 2 GPa, in good agreement with our theoretical simulations. Furthermore, our measurements suggest that in finite magnetic field due to pressure a topologically nontrivial band gap opens at the charge neutrality point at zero displacement field.
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Affiliation(s)
- Bálint Szentpéteri
- Department
of Physics, Budapest University of Technology
and Economics and Nanoelectronics Momentum Research Group of the Hungarian
Academy of Sciences, Budafoki ut 8, 1111 Budapest, Hungary
| | - Peter Rickhaus
- Solid
State Physics Laboratory, ETH Zürich, CH-8093 Zürich, Switzerland
| | | | - Albin Márffy
- Department
of Physics, Budapest University of Technology
and Economics and Correlated van der Waals Structures Momentum Research
Group of the Hungarian Academy of Sciences, Budafoki ut 8, 1111 Budapest, Hungary
| | - Bálint Fülöp
- Department
of Physics, Budapest University of Technology
and Economics and Nanoelectronics Momentum Research Group of the Hungarian
Academy of Sciences, Budafoki ut 8, 1111 Budapest, Hungary
| | - Endre Tóvári
- Department
of Physics, Budapest University of Technology
and Economics and Nanoelectronics Momentum Research Group of the Hungarian
Academy of Sciences, Budafoki ut 8, 1111 Budapest, Hungary
| | - 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
| | - Andor Kormányos
- Department
of Physics of Complex Systems, Eötvös
Loránd University, Pázmány P. s. 1/A, 1117 Budapest, Hungary
| | - Szabolcs Csonka
- Department
of Physics, Budapest University of Technology
and Economics and Nanoelectronics Momentum Research Group of the Hungarian
Academy of Sciences, Budafoki ut 8, 1111 Budapest, Hungary
| | - Péter Makk
- Department
of Physics, Budapest University of Technology
and Economics and Correlated van der Waals Structures Momentum Research
Group of the Hungarian Academy of Sciences, Budafoki ut 8, 1111 Budapest, Hungary
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25
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Rickhaus P, de Vries FK, Zhu J, Portoles E, Zheng G, Masseroni M, Kurzmann A, Taniguchi T, Watanabe K, MacDonald AH, Ihn T, Ensslin K. Correlated electron-hole state in twisted double-bilayer graphene. Science 2021; 373:1257-1260. [PMID: 34516786 DOI: 10.1126/science.abc3534] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Peter Rickhaus
- Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich, Switzerland
| | | | - Jihang Zhu
- Department of Physics, University of Texas at Austin, Austin, TX 78712, USA
| | - Elías Portoles
- Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Giulia Zheng
- Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Michele Masseroni
- Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Annika Kurzmann
- Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Takashi Taniguchi
- National Institute for Material Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Kenji Watanabe
- National Institute for Material Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Allan H MacDonald
- Department of Physics, University of Texas at Austin, Austin, TX 78712, USA
| | - Thomas Ihn
- Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich, Switzerland.,Quantum Center, ETH Zürich, 8093 Zürich, Switzerland
| | - Klaus Ensslin
- Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich, Switzerland.,Quantum Center, ETH Zürich, 8093 Zürich, Switzerland
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