1
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Bhowmik S, Ghosh A, Chandni U. Emergent phases in graphene flat bands. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2024; 87:096401. [PMID: 39059412 DOI: 10.1088/1361-6633/ad67ed] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 07/26/2024] [Indexed: 07/28/2024]
Abstract
Electronic correlations in two-dimensional materials play a crucial role in stabilising emergent phases of matter. The realisation of correlation-driven phenomena in graphene has remained a longstanding goal, primarily due to the absence of strong electron-electron interactions within its low-energy bands. In this context, magic-angle twisted bilayer graphene has recently emerged as a novel platform featuring correlated phases favoured by the low-energy flat bands of the underlying moiré superlattice. Notably, the observation of correlated insulators and superconductivity, and the interplay between these phases have garnered significant attention. A wealth of correlated phases with unprecedented tunability was discovered subsequently, including orbital ferromagnetism, Chern insulators, strange metallicity, density waves, and nematicity. However, a comprehensive understanding of these closely competing phases remains elusive. The ability to controllably twist and stack multiple graphene layers has enabled the creation of a whole new family of moiré superlattices with myriad properties. Here, we review the progress and development achieved so far, encompassing the rich phase diagrams offered by these graphene-based moiré systems. Additionally, we discuss multiple phases recently observed in non-moiré multilayer graphene systems. Finally, we outline future opportunities and challenges for the exploration of hidden phases in this new generation of moiré materials.
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Affiliation(s)
- Saisab Bhowmik
- Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012, India
| | - Arindam Ghosh
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
- Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012, India
| | - U Chandni
- Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012, India
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2
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Yang B, Dong W, Zhu C, Huang X, Han Y, Zheng Y, Yan J, Zhuang Z, Yu Y. Reinforcing 2D Single-Crystal Bi 2O 2CO 3 with Additional Interlayer Carbonates by CO 2-Assisted Solid-to-Solid Phase Transition. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2401559. [PMID: 38659393 DOI: 10.1002/smll.202401559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 04/01/2024] [Indexed: 04/26/2024]
Abstract
A facile gaseous CO2 mediated solid-to-solid transformation principle is adopted to insert additional CO3 2- anions into the thin single-crystal nanosheets of Bi2O2CO3, which is built of periodic arrays of intrinsic CO3 2- anions and (Bi2O2)2+ layers. The additional CO3 2- anions create abundant defects. The Bi2O2CO3 nanosheets with rich interlayer CO3 2- exhibit superior electronic properties and charge transfer kinetics than the pristine single-crystal 2D Bi2O2CO3 and display enhanced catalytic activity in photocatalytic CO2 reduction reaction and the photocatalytic oxidative degradation of organic pollutants. This work thus illustrates interlayer engineering as a flexible means to build layered 2D materials with excellent properties.
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Affiliation(s)
- Bixia Yang
- College of Materials Science and Engineering, Fuzhou University, New Campus, Minhou, Fujian, 350108, China
- Key Laboratory of Advanced Materials Technologies, Fuzhou University, Fuzhou, 350108, China
| | - Weilong Dong
- College of Materials Science and Engineering, Fuzhou University, New Campus, Minhou, Fujian, 350108, China
- Key Laboratory of Advanced Materials Technologies, Fuzhou University, Fuzhou, 350108, China
| | - Chongbing Zhu
- AQUA Worth (Suzhou) Environmental Protection Co.,Ltd, Suzhou, 215011, China
| | - Xinlian Huang
- College of Materials Science and Engineering, Fuzhou University, New Campus, Minhou, Fujian, 350108, China
- Key Laboratory of Advanced Materials Technologies, Fuzhou University, Fuzhou, 350108, China
| | - Yunhui Han
- College of Materials Science and Engineering, Fuzhou University, New Campus, Minhou, Fujian, 350108, China
- Key Laboratory of Advanced Materials Technologies, Fuzhou University, Fuzhou, 350108, China
| | - Yanting Zheng
- College of Materials Science and Engineering, Fuzhou University, New Campus, Minhou, Fujian, 350108, China
- Key Laboratory of Advanced Materials Technologies, Fuzhou University, Fuzhou, 350108, China
| | - Jiawei Yan
- College of Materials Science and Engineering, Fuzhou University, New Campus, Minhou, Fujian, 350108, China
- Key Laboratory of Advanced Materials Technologies, Fuzhou University, Fuzhou, 350108, China
| | - Zanyong Zhuang
- College of Materials Science and Engineering, Fuzhou University, New Campus, Minhou, Fujian, 350108, China
- Key Laboratory of Advanced Materials Technologies, Fuzhou University, Fuzhou, 350108, China
| | - Yan Yu
- College of Materials Science and Engineering, Fuzhou University, New Campus, Minhou, Fujian, 350108, China
- Key Laboratory of Advanced Materials Technologies, Fuzhou University, Fuzhou, 350108, China
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3
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Shi Y, Gong Y, Zhang Y, Li Y, Li X, Tan Z, Fan L. Axially Growing Carbon Quantum Ribbon with 2D Stacking Control for High-Stability Solar Cell. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2400817. [PMID: 39031527 DOI: 10.1002/advs.202400817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 03/29/2024] [Indexed: 07/22/2024]
Abstract
Although power conversion efficiency (PCE) of solar cells (SCs) continues to improve, they are still far from practical application because of their complex synthesis process, high cost and inferior operational stability. Carbon quantum dots with high material stability and remarkable photoluminescence are successfully used in light-emitting diodes. A good light emitter should also be an efficient SC according to the photon balance in Shockley-Quieisser formulation, in which all excitons are ultimately separated. However, the finite quantum-sized sp2 domain leads to tight exciton bonding, and highly delocalized electron clouds in irregular molecular stacks form disordered charge transfer, resulting in severe energy loss. Herein, an axially growing carbon quantum ribbon (AG-CQR) with a wide optical absorption range of 440-850 nm is reported. Structural and computational studies reveal that AG-CQRs (aspect ratio ≈2:1) with carbonyl groups at both ends regulate energy level and efficiently separate excitons. The stacking-controlled two-dimensional AG-CQR film further directionally transfers electrons and holes, particularly in AB stacking mode. Using this film as active layer alone, the SCs yield a maximum PCE of 1.22%, impressive long-term operational stability of 380 h, and repeatability. This study opens the door for the development of new-generation carbon-nanomaterial-based SCs for practical applications.
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Affiliation(s)
- Yuxin Shi
- Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, 100875, China
| | - Yongshuai Gong
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering Department, Beijing University of Chemical Technology Institution, Beijing, 100029, China
| | - Yang Zhang
- Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, 100875, China
| | - Yunchao Li
- Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, 100875, China
| | - Xiaohong Li
- Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, 100875, China
| | - Zhan'ao Tan
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering Department, Beijing University of Chemical Technology Institution, Beijing, 100029, China
| | - Louzhen Fan
- Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, 100875, China
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4
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Devarakonda A, Chen A, Fang S, Graf D, Kriener M, Akey AJ, Bell DC, Suzuki T, Checkelsky JG. Evidence of striped electronic phases in a structurally modulated superlattice. Nature 2024; 631:526-530. [PMID: 38961299 DOI: 10.1038/s41586-024-07589-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 05/21/2024] [Indexed: 07/05/2024]
Abstract
The electronic properties of crystals can be manipulated by superimposing spatially periodic electric, magnetic or structural modulations. Long-wavelength modulations incommensurate with the atomic lattice are particularly interesting1, exemplified by recent advances in two-dimensional (2D) moiré materials2,3. Bulk van der Waals (vdW) superlattices4-8 hosting 2D interfaces between minimally disordered layers represent scalable bulk analogues of artificial vdW heterostructures and present a complementary venue to explore incommensurately modulated 2D states. Here we report the bulk vdW superlattice SrTa2S5 realizing an incommensurate one-dimensional (1D) structural modulation of 2D transition metal dichalcogenide (TMD) H-TaS2 layers. High-quality electronic transport in the H-TaS2 layers, evidenced by quantum oscillations, is made anisotropic by the modulation and exhibits commensurability oscillations paralleling lithographically modulated 2D systems9-11. We also find unconventional, clean-limit superconductivity in SrTa2S5 with a pronounced suppression of interlayer relative to intralayer coherence. The in-plane magnetic field dependence of interlayer critical current, together with electron diffraction from the structural modulation, suggests superconductivity12-14 in SrTa2S5 is spatially modulated and mismatched between adjacent TMD layers. With phenomenology suggestive of pair-density wave superconductivity15-17, SrTa2S5 may present a pathway for microscopic evaluation of this unconventional order18-21. More broadly, SrTa2S5 establishes bulk vdW superlattices as versatile platforms to address long-standing predictions surrounding modulated electronic phases in the form of nanoscale vdW devices12,13 to macroscopic crystals22,23.
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Affiliation(s)
- A Devarakonda
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, USA
| | - A Chen
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - S Fang
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - D Graf
- National High Magnetic Field Laboratory, Tallahassee, FL, USA
| | - M Kriener
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
| | - A J Akey
- Center for Nanoscale Systems, Harvard University, Cambridge, MA, USA
| | - D C Bell
- Center for Nanoscale Systems, Harvard University, Cambridge, MA, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - T Suzuki
- Department of Physics, Toho University, Funabashi, Japan
| | - J G Checkelsky
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
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5
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Hou Y, Zhou J, Xue M, Yu M, Han Y, Zhang Z, Lu Y. Strain Engineering of Twisted Bilayer Graphene: The Rise of Strain-Twistronics. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2311185. [PMID: 38616775 DOI: 10.1002/smll.202311185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Revised: 03/24/2024] [Indexed: 04/16/2024]
Abstract
The layer-by-layer stacked van der Waals structures (termed vdW hetero/homostructures) offer a new paradigm for materials design-their physical properties can be tuned by the vertical stacking sequence as well as by adding a mechanical twist, stretch, and hydrostatic pressure to the atomic structure. In particular, simple twisting and stacking of two layers of graphene can form a uniform and ordered Moiré superlattice, which can effectively modulate the electrons of graphene layers and lead to the discovery of unconventional superconductivity and strong correlations. However, the twist angle of twisted bilayer graphene (tBLG) is almost unchangeable once the interlayer stacking is determined, while applying mechanical elastic strain provides an alternative way to deeply regulate the electronic structure by controlling the lattice spacing and symmetry. In this review, diverse experimental advances are introduced in straining tBLG by in-plane and out-of-plane modes, followed by the characterizations and calculations toward quantitatively tuning the strain-engineered electronic structures. It is further discussed that the structural relaxation in strained Moiré superlattice and its influence on electronic structures. Finally, the conclusion entails prospects for opportunities of strained twisted 2D materials, discussions on existing challenges, and an outlook on the intriguing emerging field, namely "strain-twistronics".
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Affiliation(s)
- Yuan Hou
- Department of Mechanical Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR, 999077, China
| | - Jingzhuo Zhou
- Department of Mechanical Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR, 999077, China
| | - Minmin Xue
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, State Key Laboratory of Mechanics and Control of Mechanical Structures, and Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China
| | - Maolin Yu
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, State Key Laboratory of Mechanics and Control of Mechanical Structures, and Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China
| | - Ying Han
- Department of Mechanical Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR, 999077, China
| | - Zhuhua Zhang
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, State Key Laboratory of Mechanics and Control of Mechanical Structures, and Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China
| | - Yang Lu
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong, Hong Kong SAR, 999077, China
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6
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Craig IM, Van Winkle M, Groschner C, Zhang K, Dowlatshahi N, Zhu Z, Taniguchi T, Watanabe K, Griffin SM, Bediako DK. Local atomic stacking and symmetry in twisted graphene trilayers. NATURE MATERIALS 2024; 23:323-330. [PMID: 38191631 DOI: 10.1038/s41563-023-01783-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Accepted: 12/08/2023] [Indexed: 01/10/2024]
Abstract
Moiré superlattices formed by twisting trilayers of graphene are a useful model for studying correlated electron behaviour and offer several advantages over their formative bilayer analogues, including a more diverse collection of correlated phases and more robust superconductivity. Spontaneous structural relaxation alters the behaviour of moiré superlattices considerably and has been suggested to play an important role in the relative stability of superconductivity in trilayers. Here we use an interferometric four-dimensional scanning transmission electron microscopy approach to directly probe the local graphene layer alignment over a wide range of trilayer graphene structures. Our results inform a thorough understanding of how reconstruction modulates the local lattice symmetries crucial for establishing correlated phases in twisted graphene trilayers, evincing a relaxed structure that is markedly different from that proposed previously.
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Affiliation(s)
- Isaac M Craig
- Department of Chemistry, University of California, Berkeley, CA, USA
| | | | | | - Kaidi Zhang
- Department of Chemistry, University of California, Berkeley, CA, USA
| | | | - Ziyan Zhu
- SLAC National Accelerator Laboratory, Stanford, CA, USA
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Kenji Watanabe
- Research for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Sinéad M Griffin
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - D Kwabena Bediako
- Department of Chemistry, University of California, Berkeley, CA, USA.
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
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7
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Luo R, Zhou W. Unveiling the intricate moiré of moiré texture. NATURE MATERIALS 2024; 23:304-305. [PMID: 38438617 DOI: 10.1038/s41563-024-01805-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2024]
Affiliation(s)
- Ruichun Luo
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Wu Zhou
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China.
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8
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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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9
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Zhang Y, Hou W, Chang R, Yao X, Xu Y. Ultrafast alternating-current exfoliation toward large-scale synthesis of graphene and its application for flexible supercapacitors. J Colloid Interface Sci 2024; 654:246-257. [PMID: 37839241 DOI: 10.1016/j.jcis.2023.10.030] [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: 07/26/2023] [Revised: 09/30/2023] [Accepted: 10/08/2023] [Indexed: 10/17/2023]
Abstract
To facilitate the transition of laboratory research to industrial applications, it is critical to establish a reliable protocol for the mass synthesis of high-quality graphene. Here, we present an efficient electrochemical intercalation-based exfoliation approach utilizing alternating current that allows for the production of sub-kilogram quantities of graphene. This strategy involves repeatedly intercalating foreign anions and cations into the interlayer gaps of dual-graphite electrodes, accelerating the graphite expansion process and maximizing the exfoliation efficiency of both electrodes while inhibiting excessive anodic oxidation. The exfoliation process leads to high-yield graphene nanosheets (92 %, primarily 1-3 layers) with minimal structural deterioration (ID/IG ratio of 0.05), high purity (2.1 at% oxygen), and outstanding electrical property (7.28 × 104 S m-1). Notably, our scaled-up manufacturing technique produces a record-breaking throughput of 135 g h-1, improving on the best-reported exfoliation efficiency with direct current by 35%. Furthermore, the as-made graphene demonstrates a large reversible capacity of 102 mF cm-2 for flexible supercapacitors, with robust cyclability with 99.5% after 10,000 cycles, excellent mechanical flexibility, and exceptional serial integration for adjustable voltage output. The efficient and scalable method presents a significant advancement in the large-scale manufacture of graphene, with potential for widespread industrial applications.
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Affiliation(s)
- Yuan Zhang
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China; Shaanxi Engineering Research Center of Advanced Energy Materials & Devices, School of Electronic Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China; National Innovation Platform (Center) for Industry-Education Integration of Energy Storage Technology, Xi'an Jiaotong University, Xi'an 710049, China
| | - Wenqiang Hou
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China; Shaanxi Engineering Research Center of Advanced Energy Materials & Devices, School of Electronic Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China; National Innovation Platform (Center) for Industry-Education Integration of Energy Storage Technology, Xi'an Jiaotong University, Xi'an 710049, China
| | - Rui Chang
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China; Shaanxi Engineering Research Center of Advanced Energy Materials & Devices, School of Electronic Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China; National Innovation Platform (Center) for Industry-Education Integration of Energy Storage Technology, Xi'an Jiaotong University, Xi'an 710049, China
| | - Xianghua Yao
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China; Shaanxi Engineering Research Center of Advanced Energy Materials & Devices, School of Electronic Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China; National Innovation Platform (Center) for Industry-Education Integration of Energy Storage Technology, Xi'an Jiaotong University, Xi'an 710049, China
| | - Youlong Xu
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China; Shaanxi Engineering Research Center of Advanced Energy Materials & Devices, School of Electronic Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China; National Innovation Platform (Center) for Industry-Education Integration of Energy Storage Technology, Xi'an Jiaotong University, Xi'an 710049, China.
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10
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Zhou H, Auerbach N, Uzan M, Zhou Y, Banu N, Zhi W, Huber ME, Watanabe K, Taniguchi T, Myasoedov Y, Yan B, Zeldov E. Imaging quantum oscillations and millitesla pseudomagnetic fields in graphene. Nature 2023; 624:275-281. [PMID: 37993718 PMCID: PMC10719110 DOI: 10.1038/s41586-023-06763-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Accepted: 10/19/2023] [Indexed: 11/24/2023]
Abstract
The exceptional control of the electronic energy bands in atomically thin quantum materials has led to the discovery of several emergent phenomena1. However, at present there is no versatile method for mapping the local band structure in advanced two-dimensional materials devices in which the active layer is commonly embedded in the insulating layers and metallic gates. Using a scanning superconducting quantum interference device, here we image the de Haas-van Alphen quantum oscillations in a model system, the Bernal-stacked trilayer graphene with dual gates, which shows several highly tunable bands2-4. By resolving thermodynamic quantum oscillations spanning more than 100 Landau levels in low magnetic fields, we reconstruct the band structure and its evolution with the displacement field with excellent precision and nanoscale spatial resolution. Moreover, by developing Landau-level interferometry, we show shear-strain-induced pseudomagnetic fields and map their spatial dependence. In contrast to artificially induced large strain, which leads to pseudomagnetic fields of hundreds of tesla5-7, we detect naturally occurring pseudomagnetic fields as low as 1 mT corresponding to graphene twisting by 1 millidegree, two orders of magnitude lower than the typical angle disorder in twisted bilayer graphene8-11. This ability to resolve the local band structure and strain at the nanoscale level enables the characterization and use of tunable band engineering in practical van der Waals devices.
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Affiliation(s)
- Haibiao Zhou
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Nadav Auerbach
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Matan Uzan
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Yaozhang Zhou
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Nasrin Banu
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Weifeng Zhi
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Martin E Huber
- Departments of Physics and Electrical Engineering, University of Colorado Denver, Denver, CO, USA
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Yuri Myasoedov
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Binghai Yan
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Eli Zeldov
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel.
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11
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Kim H, Choi Y, Lantagne-Hurtubise É, Lewandowski C, Thomson A, Kong L, Zhou H, Baum E, Zhang Y, Holleis L, Watanabe K, Taniguchi T, Young AF, Alicea J, Nadj-Perge S. Imaging inter-valley coherent order in magic-angle twisted trilayer graphene. Nature 2023; 623:942-948. [PMID: 37968401 DOI: 10.1038/s41586-023-06663-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 09/21/2023] [Indexed: 11/17/2023]
Abstract
Magic-angle twisted trilayer graphene (MATTG) exhibits a range of strongly correlated electronic phases that spontaneously break its underlying symmetries1,2. Here we investigate the correlated phases of MATTG using scanning tunnelling microscopy and identify marked signatures of interaction-driven spatial symmetry breaking. In low-strain samples, over a filling range of about two to three electrons or holes per moiré unit cell, we observe atomic-scale reconstruction of the graphene lattice that accompanies a correlated gap in the tunnelling spectrum. This short-scale restructuring appears as a Kekulé supercell-implying spontaneous inter-valley coherence between electrons-and persists in a wide range of magnetic fields and temperatures that coincide with the development of the gap. Large-scale maps covering several moiré unit cells further reveal a slow evolution of the Kekulé pattern, indicating that atomic-scale reconstruction coexists with translation symmetry breaking at a much longer moiré scale. We use auto-correlation and Fourier analyses to extract the intrinsic periodicity of these phases and find that they are consistent with the theoretically proposed incommensurate Kekulé spiral order3,4. Moreover, we find that the wavelength characterizing moiré-scale modulations monotonically decreases with hole doping away from half-filling of the bands and depends weakly on the magnetic field. Our results provide essential insights into the nature of the correlated phases of MATTG in the presence of strain and indicate that superconductivity can emerge from an inter-valley coherent parent state.
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Affiliation(s)
- Hyunjin Kim
- Thomas J. Watson, Sr, Laboratories of Applied Physics, California Institute of Technology, Pasadena, CA, USA.
- Department of Physics, California Institute of Technology, Pasadena, CA, USA.
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, CA, USA.
| | - Youngjoon Choi
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, USA
| | - Étienne Lantagne-Hurtubise
- Department of Physics, California Institute of Technology, Pasadena, CA, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, CA, USA
| | - Cyprian Lewandowski
- Department of Physics, California Institute of Technology, Pasadena, CA, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, CA, USA
- National High Magnetic Field Laboratory, Tallahassee, FL, USA
- Department of Physics, Florida State University, Tallahassee, FL, USA
| | - Alex Thomson
- Department of Physics, California Institute of Technology, Pasadena, CA, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, CA, USA
- Walter Burke Institute for Theoretical Physics, California Institute of Technology, Pasadena, CA, USA
- Department of Physics, University of California, Davis, Davis, CA, USA
| | - Lingyuan Kong
- Thomas J. Watson, Sr, Laboratories of Applied Physics, California Institute of Technology, Pasadena, CA, USA
- Department of Physics, California Institute of Technology, Pasadena, CA, USA
| | - Haoxin Zhou
- Thomas J. Watson, Sr, Laboratories of Applied Physics, California Institute of Technology, Pasadena, CA, USA
- Department of Physics, California Institute of Technology, Pasadena, CA, USA
| | - Eli Baum
- Thomas J. Watson, Sr, Laboratories of Applied Physics, California Institute of Technology, Pasadena, CA, USA
- Department of Physics, California Institute of Technology, Pasadena, CA, USA
| | - Yiran Zhang
- Thomas J. Watson, Sr, Laboratories of Applied Physics, California Institute of Technology, Pasadena, CA, USA
- Department of Physics, California Institute of Technology, Pasadena, CA, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, CA, USA
| | - Ludwig Holleis
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, USA
| | - Kenji Watanabe
- Department of Physics, University of California, Davis, Davis, CA, USA
| | | | - Andrea F Young
- National Institute for Materials Science, Tsukuba, Ibaraki, Japan
| | - Jason Alicea
- Department of Physics, California Institute of Technology, Pasadena, CA, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, CA, USA
- Walter Burke Institute for Theoretical Physics, California Institute of Technology, Pasadena, CA, USA
| | - Stevan Nadj-Perge
- Thomas J. Watson, Sr, Laboratories of Applied Physics, California Institute of Technology, Pasadena, CA, USA.
- Department of Physics, California Institute of Technology, Pasadena, CA, USA.
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12
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Li Y, Wan Q, Xu N. Recent Advances in Moiré Superlattice Systems by Angle-Resolved Photoemission Spectroscopy. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023:e2305175. [PMID: 37689836 DOI: 10.1002/adma.202305175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 08/16/2023] [Indexed: 09/11/2023]
Abstract
The last decade has witnessed a flourish in 2D materials including graphene and transition metal dichalcogenides (TMDs) as atomic-scale Legos. Artificial moiré superlattices via stacking 2D materials with a twist angle and/or a lattice mismatch have recently become a fertile playground exhibiting a plethora of emergent properties beyond their building blocks. These rich quantum phenomena stem from their nontrivial electronic structures that are effectively tuned by the moiré periodicity. Modern angle-resolved photoemission spectroscopy (ARPES) can directly visualize electronic structures with decent momentum, energy, and spatial resolution, thus can provide enlightening insights into fundamental physics in moiré superlattice systems and guides for designing novel devices. In this review, first, a brief introduction is given on advanced ARPES techniques and basic ideas of band structures in a moiré superlattice system. Then ARPES research results of various moiré superlattice systems are highlighted, including graphene on substrates with small lattice mismatches, twisted graphene/TMD moiré systems, and high-order moiré superlattice systems. Finally, it discusses important questions that remain open, challenges in current experimental investigations, and presents an outlook on this field of research.
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Affiliation(s)
- Yiwei Li
- Institute for Advanced Studies (IAS), Wuhan University, Wuhan, 430072, China
| | - Qiang Wan
- Institute for Advanced Studies (IAS), Wuhan University, Wuhan, 430072, China
| | - Nan Xu
- Institute for Advanced Studies (IAS), Wuhan University, Wuhan, 430072, China
- Wuhan Institute of Quantum Technology, Wuhan, 430206, China
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13
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Devakul T, Ledwith PJ, Xia LQ, Uri A, de la Barrera SC, Jarillo-Herrero P, Fu L. Magic-angle helical trilayer graphene. SCIENCE ADVANCES 2023; 9:eadi6063. [PMID: 37672575 PMCID: PMC10482339 DOI: 10.1126/sciadv.adi6063] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Accepted: 08/02/2023] [Indexed: 09/08/2023]
Abstract
We propose magic-angle helical trilayer graphene (HTG), a helical structure featuring identical rotation angles between three consecutive layers of graphene, as a unique and experimentally accessible platform for realizing exotic correlated topological states of matter. While nominally forming a supermoiré (or moiré-of-moiré) structure, we show that HTG locally relaxes into large regions of a periodic single-moiré structure realizing flat topological bands carrying nontrivial valley Chern number. These bands feature near-ideal quantum geometry and are isolated from remote bands by a very large energy gap, making HTG a promising platform for experimental realization of correlated topological states such as integer and fractional quantum anomalous Hall states.
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Affiliation(s)
- Trithep Devakul
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Physics, Stanford University, Stanford, CA 94305, USA
| | | | - Li-Qiao Xia
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Aviram Uri
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Sergio C. de la Barrera
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Physics, University of Toronto, Toronto, ON M5S 1A7, Canada
| | - Pablo Jarillo-Herrero
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Liang Fu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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14
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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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15
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Uri A, de la Barrera SC, Randeria MT, Rodan-Legrain D, Devakul T, Crowley PJD, Paul N, Watanabe K, Taniguchi T, Lifshitz R, Fu L, Ashoori RC, Jarillo-Herrero P. Superconductivity and strong interactions in a tunable moiré quasicrystal. Nature 2023; 620:762-767. [PMID: 37468640 DOI: 10.1038/s41586-023-06294-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 06/07/2023] [Indexed: 07/21/2023]
Abstract
Electronic states in quasicrystals generally preclude a Bloch description1, rendering them fascinating and enigmatic. Owing to their complexity and scarcity, quasicrystals are underexplored relative to periodic and amorphous structures. Here we introduce a new type of highly tunable quasicrystal easily assembled from periodic components. By twisting three layers of graphene with two different twist angles, we form two mutually incommensurate moiré patterns. In contrast to many common atomic-scale quasicrystals2,3, the quasiperiodicity in our system is defined on moiré length scales of several nanometres. This 'moiré quasicrystal' allows us to tune the chemical potential and thus the electronic system between a periodic-like regime at low energies and a strongly quasiperiodic regime at higher energies, the latter hosting a large density of weakly dispersing states. Notably, in the quasiperiodic regime, we observe superconductivity near a flavour-symmetry-breaking phase transition4,5, the latter indicative of the important role that electronic interactions play in that regime. The prevalence of interacting phenomena in future systems with in situ tunability is not only useful for the study of quasiperiodic systems but may also provide insights into electronic ordering in related periodic moiré crystals6-12. We anticipate that extending this platform to engineer quasicrystals by varying the number of layers and twist angles, and by using different two-dimensional components, will lead to a new family of quantum materials to investigate the properties of strongly interacting quasicrystals.
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Affiliation(s)
- Aviram Uri
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | | | - Mallika T Randeria
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Daniel Rodan-Legrain
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Trithep Devakul
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Philip J D Crowley
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Nisarga Paul
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - 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
| | - Ron Lifshitz
- Raymond & Beverly Sackler School of Physics & Astronomy, Tel Aviv University, Tel Aviv, Israel
| | - Liang Fu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Raymond C Ashoori
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
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16
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Craig IM, Van Winkle M, Groschner C, Zhang K, Dowlatshahi N, Taniguchi T, Watanabe K, Griffin S, Bediako DK. Interferometric Imaging of Twisted Trilayer Graphene Moiré Superlattices. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:1641. [PMID: 37613927 DOI: 10.1093/micmic/ozad067.844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- Isaac M Craig
- Department of Chemistry, University of California, Berkeley, CA, USA
| | | | | | - Kaidi Zhang
- Department of Chemistry, University of California, Berkeley, CA, USA
| | | | - Takashi Taniguchi
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Kenji Watanabe
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Sinéad Griffin
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - D Kwabena Bediako
- Department of Chemistry, University of California, Berkeley, CA, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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17
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Sainz-Cruz H, Pantaleón PA, Phong VT, Jimeno-Pozo A, Guinea F. Junctions and Superconducting Symmetry in Twisted Bilayer Graphene. PHYSICAL REVIEW LETTERS 2023; 131:016003. [PMID: 37478460 DOI: 10.1103/physrevlett.131.016003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 05/31/2023] [Indexed: 07/23/2023]
Abstract
Junctions provide a wealth of information on the symmetry of the order parameter of superconductors. We analyze junctions between a scanning tunneling microscope (STM) tip and superconducting twisted bilayer graphene (TBG) and TBG Josephson junctions (JJs). We compare superconducting phases that are even or odd under valley exchange (s- or f-wave). The critical current in mixed (s and f) JJs strongly depends on the angle between the junction and the lattice. In STM-TBG junctions, due to Andreev reflection, the f-wave leads to a prominent peak in subgap conductance, as seen in experiments.
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Affiliation(s)
| | | | - Võ Tiến Phong
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | | | - Francisco Guinea
- Imdea Nanoscience, Faraday 9, 28015 Madrid, Spain
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastian, Spain
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18
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Zhang K, Yu Y, Carr S, Babar M, Zhu Z, Kim BJ, Groschner C, Khaloo N, Taniguchi T, Watanabe K, Viswanathan V, Bediako DK. Anomalous Interfacial Electron-Transfer Kinetics in Twisted Trilayer Graphene Caused by Layer-Specific Localization. ACS CENTRAL SCIENCE 2023; 9:1119-1128. [PMID: 37396866 PMCID: PMC10311658 DOI: 10.1021/acscentsci.3c00326] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Indexed: 07/04/2023]
Abstract
Interfacial electron-transfer (ET) reactions underpin the interconversion of electrical and chemical energy. It is known that the electronic state of electrodes strongly influences ET rates because of differences in the electronic density of states (DOS) across metals, semimetals, and semiconductors. Here, by controlling interlayer twists in well-defined trilayer graphene moirés, we show that ET rates are strikingly dependent on electronic localization in each atomic layer and not the overall DOS. The large degree of tunability inherent to moiré electrodes leads to local ET kinetics that range over 3 orders of magnitude across different constructions of only three atomic layers, even exceeding rates at bulk metals. Our results demonstrate that beyond the ensemble DOS, electronic localization is critical in facilitating interfacial ET, with implications for understanding the origin of high interfacial reactivity typically exhibited by defects at electrode-electrolyte interfaces.
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Affiliation(s)
- Kaidi Zhang
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Yun Yu
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Stephen Carr
- Brown
Theoretical Physics Center, Brown University, Providence, Rhode Island 02912, United States
| | - Mohammad Babar
- Department
of Mechanical Engineering, Carnegie Mellon
University, Pittsburgh, Pennsylvania 15213, United States
| | - Ziyan Zhu
- SLAC
National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Bryan Junsuh Kim
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Catherine Groschner
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Nikta Khaloo
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Takashi Taniguchi
- International
Center for Materials Nanoarchitectonics, National Institute for Materials Science, 305-0044 Tsukuba, Japan
| | - Kenji Watanabe
- Research
Center for Functional Materials, National
Institute for Materials Science, 305-0044 Tsukuba, Japan
| | | | - D. Kwabena Bediako
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
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19
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Guo Y, Qiu D, Shao M, Song J, Wang Y, Xu M, Yang C, Li P, Liu H, Xiong J. Modulations in Superconductors: Probes of Underlying Physics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2209457. [PMID: 36504310 DOI: 10.1002/adma.202209457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/16/2022] [Indexed: 06/02/2023]
Abstract
The importance of modulations is elevated to an unprecedented level, due to the delicate conditions required to bring out exotic phenomena in quantum materials, such as topological materials, magnetic materials, and superconductors. Recently, state-of-the-art modulation techniques in material science, such as electric-double-layer transistor, piezoelectric-based strain apparatus, angle twisting, and nanofabrication, have been utilized in superconductors. They not only efficiently increase the tuning capability to the broader ranges but also extend the tuning dimensionality to unprecedented degrees of freedom, including quantum fluctuations of competing phases, electronic correlation, and phase coherence essential to global superconductivity. Here, for a comprehensive review, these techniques together with the established modulation methods, such as elemental substitution, annealing, and polarization-induced gating, are contextualized. Depending on the mechanism of each method, the modulations are categorized into stoichiometric manipulation, electrostatic gating, mechanical modulation, and geometrical design. Their recent advances are highlighted by applications in newly discovered superconductors, e.g., nickelates, Kagome metals, and magic-angle graphene. Overall, the review is to provide systematic modulations in emergent superconductors and serve as the coordinate for future investigations, which can stimulate researchers in superconductivity and other fields to perform various modulations toward a thorough understanding of quantum materials.
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Affiliation(s)
- Yehao Guo
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Dong Qiu
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Mingxin Shao
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Jingyan Song
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Yang Wang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Minyi Xu
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Chao Yang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Peng Li
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Haiwen Liu
- Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - Jie Xiong
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
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20
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Jiang J, Jiang W, Zhang S, Xie Y, Chen Y. Coupling double flat bands in a quadrangular-star lattice. NANOSCALE 2023; 15:8825-8831. [PMID: 37114430 DOI: 10.1039/d3nr00651d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Most special two-dimensional (2D) lattices, such as Kagome and Lieb lattices, can only generate a single flat band. Here, we propose a 2D lattice named a quadrangular-star lattice (QSL). It can produce coupling double flat bands, which indicates that there exists stronger electronic correlation than in the systems with only one flat band. Moreover, we suggest some 2D carbon allotropes (e.g. CQSL-12 and CQSL-20), made of carbon rings and dimers, to realize QSL in real materials. By calculating the band structures of the carbon materials, we find that there are indeed two coupling flat bands around the Fermi level. Hole doping leads to strong magnetism of the carbon materials. When the two flat bands are half filled, i.e., in the cases of one- and three-hole doping, the magnetic momentums mainly distribute on the atoms of the carbon rings and dimers, respectively. Even in the case of two-hole doping, the carbon structure also shows ferromagnetic characteristics, and the total magnetic moments are larger than the former two cases.
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Affiliation(s)
- Jun Jiang
- School of Physics and Electronic Engineering, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
- Jiangsu Engineering Research Center on Quantum Perception and Intelligent Detection of Agricultural Information, Zhenjiang, 212013, Jiangsu, China.
| | - Wen Jiang
- School of Physics and Electronic Engineering, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
- Jiangsu Engineering Research Center on Quantum Perception and Intelligent Detection of Agricultural Information, Zhenjiang, 212013, Jiangsu, China.
| | - Song Zhang
- School of Physics and Electronic Engineering, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
- Jiangsu Engineering Research Center on Quantum Perception and Intelligent Detection of Agricultural Information, Zhenjiang, 212013, Jiangsu, China.
| | - Yuee Xie
- School of Physics and Electronic Engineering, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
- Jiangsu Engineering Research Center on Quantum Perception and Intelligent Detection of Agricultural Information, Zhenjiang, 212013, Jiangsu, China.
| | - Yuanping Chen
- School of Physics and Electronic Engineering, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
- Jiangsu Engineering Research Center on Quantum Perception and Intelligent Detection of Agricultural Information, Zhenjiang, 212013, Jiangsu, China.
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21
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Ren YN, Zhan Z, Liu YW, Yan C, Yuan S, He L. Real-Space Mapping of Local Subdegree Lattice Rotations in Low-Angle Twisted Bilayer Graphene. NANO LETTERS 2023; 23:1836-1842. [PMID: 36799930 DOI: 10.1021/acs.nanolett.2c04710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
In two-dimensional small-angle twisted bilayers, van der Waals (vdW) interlayer interaction introduces an atomic-scale reconstruction, which consists of a moiré-periodic network of local subdegree lattice rotations. However, real-space measurement of the subdegree lattice rotation requires extremely high spatial resolution, which is an outstanding challenge in an experiment. Here, a topmost small-period graphene moiré pattern is introduced as a magnifying lens to magnify sub-Angstrom lattice distortions in small-angle twisted bilayer graphene (TBG) by about 2 orders of magnitude. Local moiré periods of the topmost graphene moiré patterns and low-energy van Hove singularities of the system are spatially modified by the atomic-scale reconstruction of the underlying TBG, thus enabling real-space mapping of the networks of the subdegree lattice rotations both in structure and in electronic properties. Our results indicate that it is quite facile to study subdegree lattice rotation in vdW systems by measuring the periods of the topmost moiré superlattice.
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Affiliation(s)
- Ya-Ning Ren
- Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Zhen Zhan
- 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
| | - Yi-Wen Liu
- Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Chao Yan
- Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
| | - 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
| | - Lin He
- Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
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22
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Scammell HD, Scheurer MS. Tunable Superconductivity and Möbius Fermi Surfaces in an Inversion-Symmetric Twisted van der Waals Heterostructure. PHYSICAL REVIEW LETTERS 2023; 130:066001. [PMID: 36827571 DOI: 10.1103/physrevlett.130.066001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 01/11/2023] [Indexed: 06/18/2023]
Abstract
We theoretically study a moiré superlattice geometry consisting of mirror-symmetric twisted trilayer graphene surrounded by identical transition metal dichalcogenide layers. We show that this setup allows us to switch on or off and control the spin-orbit splitting of the Fermi surfaces via application of a perpendicular displacement field D_{0} and explore two manifestations of this control: first, we compute the evolution of superconducting pairing with D_{0}; this features a complex admixture of singlet and triplet pairing and, depending on the pairing state in the parent trilayer system, phase transitions between competing superconducting phases. Second, we reveal that, with application of D_{0}, the spin-orbit-induced spin textures exhibit vortices which lead to "Möbius fermi surfaces" in the interior of the Brillouin zone: diabatic electron trajectories, which are predicted to dominate quantum oscillation experiments, require encircling the Γ point twice, making their Möbius nature directly observable. Further, we show that the superconducting order parameter inherits the unconventional, Möbius spin textures. Our findings suggest that this system provides a promising experimental avenue for systematically studying the impact of spin-orbit coupling on the multitude of topological and correlated phases in near-magic-angle twisted trilayer graphene.
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Affiliation(s)
- Harley D Scammell
- School of Physics, the University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Mathias S Scheurer
- Institute for Theoretical Physics, University of Innsbruck, Innsbruck A-6020, Austria
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23
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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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24
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Coordination-driven structure reconstruction in polymer of intrinsic microporosity membranes for efficient propylene/propane separation. Innovation (N Y) 2022; 3:100334. [DOI: 10.1016/j.xinn.2022.100334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 10/07/2022] [Indexed: 11/22/2022] Open
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25
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Zhang G, Wu H, Zhang L, Yang L, Xie Y, Guo F, Li H, Tao B, Wang G, Zhang W, Chang H. Two-Dimensional Van Der Waals Topological Materials: Preparation, Properties, and Device Applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2204380. [PMID: 36135779 DOI: 10.1002/smll.202204380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/23/2022] [Indexed: 06/16/2023]
Abstract
Over the past decade, 2D van der Waals (vdW) topological materials (TMs), including topological insulators and topological semimetals, which combine atomically flat 2D layers and topologically nontrivial band structures, have attracted increasing attention in condensed-matter physics and materials science. These easily cleavable and integrated TMs provide the ideal platform for exploring topological physics in the 2D limit, where new physical phenomena may emerge, and represent a potential to control and investigate exotic properties and device applications in nanoscale topological phases. However, multifaced efforts are still necessary, which is the prerequisite for the practical application of 2D vdW TMs. Herein, this review focuses on the preparation, properties, and device applications of 2D vdW TMs. First, three common preparation strategies for 2D vdW TMs are summarized, including single crystal exfoliation, chemical vapor deposition, and molecular beam epitaxy. Second, the origin and regulation of various properties of 2D vdW TMs are introduced, involving electronic properties, transport properties, optoelectronic properties, thermoelectricity, ferroelectricity, and magnetism. Third, some device applications of 2D vdW TMs are presented, including field-effect transistors, memories, spintronic devices, and photodetectors. Finally, some significant challenges and opportunities for the practical application of 2D vdW TMs in 2D topological electronics are briefly addressed.
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Affiliation(s)
- Gaojie Zhang
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Hao Wu
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Liang Zhang
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Li Yang
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Yuanmiao Xie
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Fei Guo
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Hongda Li
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Boran Tao
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Guofu Wang
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Wenfeng Zhang
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Shenzhen R&D Center of Huazhong University of Science and Technology (HUST), Shenzhen, 518000, China
| | - Haixin Chang
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Shenzhen R&D Center of Huazhong University of Science and Technology (HUST), Shenzhen, 518000, China
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26
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Li Y, Zhang S, Chen F, Wei L, Zhang Z, Xiao H, Gao H, Chen M, Liang S, Pei D, Xu L, Watanabe K, Taniguchi T, Yang L, Miao F, Liu J, Cheng B, Wang M, Chen Y, Liu Z. Observation of Coexisting Dirac Bands and Moiré Flat Bands in Magic-Angle Twisted Trilayer Graphene. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2205996. [PMID: 36043946 DOI: 10.1002/adma.202205996] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 08/10/2022] [Indexed: 06/15/2023]
Abstract
Moiré superlattices that consist of two or more layers of 2D materials stacked together with a small twist angle have emerged as a tunable platform to realize various correlated and topological phases, such as Mott insulators, unconventional superconductivity, and quantum anomalous Hall effect. Recently, magic-angle twisted trilayer graphene (MATTG) has shown both robust superconductivity similar to magic-angle twisted bilayer graphene and other unique properties, including the Pauli-limit violating and re-entrant superconductivity. These rich properties are deeply rooted in its electronic structure under the influence of distinct moiré potential and mirror symmetry. Here, combining nanometer-scale spatially resolved angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy, the as-yet unexplored band structure of MATTG near charge neutrality is systematically measured. These measurements reveal the coexistence of the distinct dispersive Dirac band with the emergent moiré flat band, showing nice agreement with the theoretical calculations. These results serve as a stepstone for further understanding of the unconventional superconductivity in MATTG.
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Affiliation(s)
- Yiwei Li
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
- Institute for Advanced Studies, Wuhan University, Luojiashan Street, Wuhan, Hubei, 430072, P. R. China
| | - Shihao Zhang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
- ShanghaiTech Laboratory for Topological Physics, Shanghai, 200031, P. R. China
| | - Fanqiang Chen
- National Laboratory of Solid State Microstructures, School of Physics, Institute of Brain-Inspired Intelligence, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China
| | - Liyang Wei
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
| | - Zonglin Zhang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
| | - Hanbo Xiao
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
| | - Han Gao
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
| | - Moyu Chen
- National Laboratory of Solid State Microstructures, School of Physics, Institute of Brain-Inspired Intelligence, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China
| | - Shijun Liang
- National Laboratory of Solid State Microstructures, School of Physics, Institute of Brain-Inspired Intelligence, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China
| | - Ding Pei
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
- ShanghaiTech Laboratory for Topological Physics, Shanghai, 200031, P. R. China
| | - Lixuan Xu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, P. R. China
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Lexian Yang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, P. R. China
- Frontier Science Center for Quantum Information, Beijing, 100084, P. R. China
| | - Feng Miao
- National Laboratory of Solid State Microstructures, School of Physics, Institute of Brain-Inspired Intelligence, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China
| | - Jianpeng Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
- ShanghaiTech Laboratory for Topological Physics, Shanghai, 200031, P. R. China
| | - Bin Cheng
- Institute of Interdisciplinary Physical Sciences, School of Science, Nanjing University of Science and Technology, Nanjing, 210094, P. R. China
| | - Meixiao Wang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
- ShanghaiTech Laboratory for Topological Physics, Shanghai, 200031, P. R. China
| | - Yulin Chen
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
- ShanghaiTech Laboratory for Topological Physics, Shanghai, 200031, P. R. China
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, P. R. China
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, OX1 3PU, UK
| | - Zhongkai Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
- ShanghaiTech Laboratory for Topological Physics, Shanghai, 200031, P. R. China
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27
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Zhang Y, Polski R, Lewandowski C, Thomson A, Peng Y, Choi Y, Kim H, Watanabe K, Taniguchi T, Alicea J, von Oppen F, Refael G, Nadj-Perge S. Promotion of superconductivity in magic-angle graphene multilayers. Science 2022; 377:1538-1543. [PMID: 36173835 DOI: 10.1126/science.abn8585] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Graphene moiré superlattices show an abundance of correlated insulating, topological, and superconducting phases. Whereas the origins of strong correlations and nontrivial topology can be directly linked to flat bands, the nature of superconductivity remains enigmatic. We demonstrate that magic-angle devices made of twisted tri-, quadri-, and pentalayer graphene placed on monolayer tungsten diselenide exhibit flavor polarization and superconductivity. We also observe insulating states in the tril- and quadrilayer arising at finite electric displacement fields. As the number of layers increases, superconductivity emerges over an enhanced filling-factor range, and in the pentalayer it extends well beyond the filling of four electrons per moiré unit cell. Our results highlight the role of the interplay between flat and more dispersive bands in extending superconducting regions in graphene moiré superlattices.
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Affiliation(s)
- Yiran Zhang
- T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Robert Polski
- T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Cyprian Lewandowski
- Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Alex Thomson
- Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Department of Physics, University of California, Davis, CA 95616, USA
| | - Yang Peng
- Department of Physics and Astronomy, California State University, Northridge, CA 91330, USA
| | - Youngjoon Choi
- T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Hyunjin Kim
- T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Kenji Watanabe
- National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305 0044, Japan
| | - Takashi Taniguchi
- National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305 0044, Japan
| | - Jason Alicea
- Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Felix von Oppen
- Dahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Gil Refael
- Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Stevan Nadj-Perge
- T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
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28
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Hong JP, Soejima T, Zaletel MP. Detecting Symmetry Breaking in Magic Angle Graphene Using Scanning Tunneling Microscopy. PHYSICAL REVIEW LETTERS 2022; 129:147001. [PMID: 36240422 DOI: 10.1103/physrevlett.129.147001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 08/20/2022] [Accepted: 08/25/2022] [Indexed: 06/16/2023]
Abstract
A growing body of experimental work suggests that magic angle twisted bilayer graphene exhibits a "cascade" of spontaneous symmetry-breaking transitions, sparking interest in the potential relationship between symmetry breaking and superconductivity. However, it has proven difficult to find experimental probes which can unambiguously identify the nature of the symmetry breaking. Here, we show how atomically resolved scanning tunneling microscopy can be used as a fingerprint of symmetry-breaking order. By analyzing the pattern of sublattice polarization and "Kekulé" distortions in small magnetic fields, order parameters for each of the most competitive symmetry-breaking states can be identified. In particular, we show that the "Kramers intervalley coherent state," which theoretical work predicts to be the ground state at even integer fillings, shows a Kekulé distortion which emerges only in a magnetic field.
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Affiliation(s)
- Jung Pyo Hong
- Department of Physics, Princeton University, Princeton, New Jersey 08540, USA
| | - Tomohiro Soejima
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Michael P Zaletel
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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29
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Choi MS, Ali N, Ngo TD, Choi H, Oh B, Yang H, Yoo WJ. Recent Progress in 1D Contacts for 2D-Material-Based Devices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2202408. [PMID: 35594170 DOI: 10.1002/adma.202202408] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 05/17/2022] [Indexed: 06/15/2023]
Abstract
Recent studies have intensively examined 2D materials (2DMs) as promising materials for use in future quantum devices due to their atomic thinness. However, a major limitation occurs when 2DMs are in contact with metals: a van der Waals (vdW) gap is generated at the 2DM-metal interfaces, which induces metal-induced gap states that are responsible for an uncontrollable Schottky barrier (SB), Fermi-level pinning (FLP), and high contact resistance (RC ), thereby substantially lowering the electronic mobility of 2DM-based devices. Here, vdW-gap-free 1D edge contact is reviewed for use in 2D devices with substantially suppressed carrier scattering of 2DMs with hexagonal boron nitride (hBN) encapsulation. The 1D contact further enables uniform carrier transport across multilayered 2DM channels, high-density transistor integration independent of scaling, and the fabrication of double-gate transistors suitable for demonstrating unique quantum phenomena of 2DMs. The existing 1D contact methods are reviewed first. As a promising technology toward the large-scale production of 2D devices, seamless lateral contacts are reviewed in detail. The electronic, optoelectronic, and quantum devices developed via 1D contacts are subsequently discussed. Finally, the challenges regarding the reliability of 1D contacts are addressed, followed by an outlook of 1D contact methods.
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Affiliation(s)
- Min Sup Choi
- SKKU Advanced Institute of Nano Technology, Sungkyunkwan University, Suwon, 16419, Korea
| | - Nasir Ali
- SKKU Advanced Institute of Nano Technology, Sungkyunkwan University, Suwon, 16419, Korea
| | - Tien Dat Ngo
- SKKU Advanced Institute of Nano Technology, Sungkyunkwan University, Suwon, 16419, Korea
| | - Hyungyu Choi
- SKKU Advanced Institute of Nano Technology, Sungkyunkwan University, Suwon, 16419, Korea
| | - Byungdu Oh
- SKKU Advanced Institute of Nano Technology, Sungkyunkwan University, Suwon, 16419, Korea
| | - Heejun Yang
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Korea
| | - Won Jong Yoo
- SKKU Advanced Institute of Nano Technology, Sungkyunkwan University, Suwon, 16419, Korea
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30
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Li Y, Xue M, Fan H, Gao CF, Shi Y, Liu Y, Watanabe K, Tanguchi T, Zhao Y, Wu F, Wang X, Shi Y, Guo W, Zhang Z, Fei Z, Li J. Symmetry Breaking and Anomalous Conductivity in a Double-Moiré Superlattice. NANO LETTERS 2022; 22:6215-6222. [PMID: 35852915 DOI: 10.1021/acs.nanolett.2c01710] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In a two-dimensional moiré superlattice, the atomic reconstruction of constituent layers could introduce significant modifications to the lattice symmetry and electronic structure at small twist angles. Here, we employ conductive atomic force microscopy to investigate a twisted trilayer graphene double-moiré superlattice. Two sets of moiré superlattices are observed. At neighboring domains of the large moiré, the current exhibits either 2- or 6-fold rotational symmetry, indicating delicate symmetry breaking beyond the rigid model. Moreover, an anomalous current appears at the "A-A" stacking site of the larger moiré, contradictory to previous observations on twisted bilayer graphene. Both behaviors can be understood by atomic reconstruction, and we also show that the measured current is dominated by the tip-graphene contact resistance that maps the local work function qualitatively. Our results reveal new insights of atomic reconstruction in novel moiré superlattices and opportunities for manipulating exotic quantum states on the basis of twisted van der Waals heterostructures.
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Affiliation(s)
- Yuhao Li
- National Laboratory of Solid-State Microstructures, School of Electronic Science and Engineering and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, Jiangsu, People's Republic of China
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, Guangdong, People's Republic of China
- State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, Jiangsu, People's Republic of China
| | - Minmin Xue
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, Institute for Frontier Science of Nanjing University of Aeronautics and Astronautics, Nanjing 210016, People's Republic of China
| | - Hua Fan
- Department of Physics, Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, Guangdong, People's Republic of China
| | - Cun-Fa Gao
- State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, Jiangsu, People's Republic of China
| | - Yan Shi
- State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, Jiangsu, People's Republic of China
| | - Yang Liu
- Jinan Institute of Quantum Technology, Jinan 250101, Shandong, People's Republic of China
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Tanguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Yue Zhao
- Department of Physics, Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, Guangdong, People's Republic of China
| | - Fengcheng Wu
- 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
| | - Xinran Wang
- National Laboratory of Solid-State Microstructures, School of Electronic Science and Engineering and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, Jiangsu, People's Republic of China
| | - Yi Shi
- National Laboratory of Solid-State Microstructures, School of Electronic Science and Engineering and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, Jiangsu, People's Republic of China
| | - Wanlin Guo
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, Institute for Frontier Science of Nanjing University of Aeronautics and Astronautics, Nanjing 210016, People's Republic of China
| | - Zhuhua Zhang
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, Institute for Frontier Science of Nanjing University of Aeronautics and Astronautics, Nanjing 210016, People's Republic of China
| | - Zaiyao Fei
- National Laboratory of Solid-State Microstructures, School of Electronic Science and Engineering and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, Jiangsu, People's Republic of China
| | - Jiangyu Li
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, Guangdong, People's Republic of China
- Guangdong Provisional Key Laboratory of Functional Oxide Materials and Devices, Southern University of Science and Technology, Shenzhen 518055, Guangdong, People's Republic of China
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31
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Burg GW, Khalaf E, Wang Y, Watanabe K, Taniguchi T, Tutuc E. Emergence of correlations in alternating twist quadrilayer graphene. NATURE MATERIALS 2022; 21:884-889. [PMID: 35798944 DOI: 10.1038/s41563-022-01286-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 05/10/2022] [Indexed: 06/15/2023]
Abstract
Alternating twist multilayer graphene (ATMG) has recently emerged as a family of moiré systems that share several fundamental properties with twisted bilayer graphene, and are expected to host similarly strong electron-electron interactions near the magic angle. Here, we study alternating twist quadrilayer graphene (ATQG) samples with twist angles of 1.96° and 1.52°, which are slightly removed from the magic angle of 1.68°. At the larger angle, we find signatures of correlated insulators only when the ATQG is hole doped, and no signatures of superconductivity, and for the smaller angle we find evidence of superconductivity, while signs of the correlated insulators weaken. Our results provide insight into the twist angle dependence of correlated phases in ATMG and shed light on the nature of correlations in the intermediate coupling regime at the edge of the magic angle range where dispersion and interaction are of the same order.
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Affiliation(s)
- G William Burg
- Microelectronics Research Center, Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Eslam Khalaf
- Department of Physics, Harvard University, Cambridge, MA, USA
- Department of Physics, The University of Texas at Austin, Austin, TX, USA
| | - Yimeng Wang
- Microelectronics Research Center, Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute of Materials Science, Ibaraki, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute of Materials Science, Ibaraki, Japan
| | - Emanuel Tutuc
- Microelectronics Research Center, Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, USA.
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Park JM, Cao Y, Xia LQ, Sun S, Watanabe K, Taniguchi T, Jarillo-Herrero P. Robust superconductivity in magic-angle multilayer graphene family. NATURE MATERIALS 2022; 21:877-883. [PMID: 35798945 DOI: 10.1038/s41563-022-01287-1] [Citation(s) in RCA: 52] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 05/10/2022] [Indexed: 06/15/2023]
Abstract
The discovery of correlated states and superconductivity in magic-angle twisted bilayer graphene (MATBG) established a new platform to explore interaction-driven and topological phenomena. However, despite multitudes of correlated phases observed in moiré systems, robust superconductivity appears the least common, found only in MATBG and more recently in magic-angle twisted trilayer graphene. Here we report the experimental realization of superconducting magic-angle twisted four-layer and five-layer graphene, hence establishing alternating twist magic-angle multilayer graphene as a robust family of moiré superconductors. This finding suggests that the flat bands shared by the members play a central role in the superconductivity. Our measurements in parallel magnetic fields, in particular the investigation of Pauli limit violation and spontaneous rotational symmetry breaking, reveal a clear distinction between the N = 2 and N > 2-layer structures, consistent with the difference between their orbital responses to magnetic fields. Our results expand the emergent family of moiré superconductors, providing new insight with potential implications for design of new superconducting materials platforms.
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Affiliation(s)
- Jeong Min Park
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Yuan Cao
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Li-Qiao Xia
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Shuwen Sun
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Kenji Watanabe
- National Institute for Materials Science, Tsukuba, Japan
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