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Shilov AL, Kashchenko MA, Pantaleón Peralta PA, Wang Y, Kravtsov M, Kudriashov A, Zhan Z, Taniguchi T, Watanabe K, Slizovskiy S, Novoselov KS, Fal'ko VI, Guinea F, Bandurin DA. High-Mobility Compensated Semimetals, Orbital Magnetization, and Umklapp Scattering in Bilayer Graphene Moiré Superlattices. ACS NANO 2024; 18:11769-11777. [PMID: 38648369 DOI: 10.1021/acsnano.3c13212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Twist-controlled moiré superlattices (MSs) have emerged as a versatile platform for realizing artificial systems with complex electronic spectra. The combination of Bernal-stacked bilayer graphene (BLG) and hexagonal boron nitride (hBN) can give rise to an interesting MS, which has recently featured a set of unexpected behaviors, such as unconventional ferroelectricity and the electronic ratchet effect. Yet, the understanding of the electronic properties of BLG/hBN MS has, at present, remained fairly limited. Here, we combine magneto-transport and low-energy sub-THz excitation to gain insights into the properties of this MS. We demonstrate that the alignment between BLG and hBN crystal lattices results in the emergence of compensated semimetals at some integer fillings of the moiré bands, separated by van Hove singularities where the Lifshitz transition occurs. A particularly pronounced semimetal develops when eight holes reside in the moiré unit cell, where coexisting high-mobility electron and hole systems feature strong magnetoresistance reaching 2350% already at B = 0.25 T. Next, by measuring the THz-driven Nernst effect in remote bands, we observe valley splitting, indicating an orbital magnetization characterized by a strongly enhanced effective gv-factor of 340. Finally, using THz photoresistance measurements, we show that the high-temperature conductivity of the BLG/hBN MS is limited by electron-electron umklapp processes. Our multifaceted analysis introduces THz-driven magnetotransport as a convenient tool to probe the band structure and interaction effects in van der Waals materials and provides a comprehensive understanding of the BLG/hBN MS.
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Affiliation(s)
- Artur L Shilov
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
| | - Mikhail A Kashchenko
- Programmable Functional Materials Lab, Center for Neurophysics and Neuromorphic Technologies, Moscow 127495, Russia
| | | | - Yibo Wang
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore 117575, Singapore
| | - Mikhail Kravtsov
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore 117575, Singapore
| | - Andrei Kudriashov
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore 117575, Singapore
| | - Zhen Zhan
- IMDEA Nanoscience, Faraday 9, Madrid 28015, Spain
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute of Material Science, Tsukuba 305-0044, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute of Material Science, Tsukuba 305-0044, Japan
| | - Sergey Slizovskiy
- School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, U.K
| | - Kostya S Novoselov
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore 117575, Singapore
| | - Vladimir I Fal'ko
- School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, U.K
| | - Francisco Guinea
- IMDEA Nanoscience, Faraday 9, Madrid 28015, Spain
- Donostia International Physics Center, Paseo Manuel de Lardizábal 4, San Sebastián 20018, Spain
| | - Denis A Bandurin
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
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Zhang W, Wu M, Zhang Y, Yan H, Lee Y, Zhao Z, Hao H, Shi X, Zhang Z, Kim K, Liu N. Paraffin-Enabled Superlattice Customization for a Photostimulated Gradient-Responsive Artificial Reflex Arc. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2313267. [PMID: 38346418 DOI: 10.1002/adma.202313267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 01/25/2024] [Indexed: 02/21/2024]
Abstract
The development of photostimulated-motion artificial reflex arcs - a neural circuit inspired by light-driven motion reflexes - holds significant promises for advancements in robotic perception, navigation, and motion control. However, the fabrication of such systems, especially those that accommodate multiple actions and exhibit gradient responses, remains challenging. Here, a gradient-responsive photostimulated-motion artificial reflex arc is developed by integrating a programmable and tunable photoreceptor based on folded MoS2 at different twist angles. The twisted folded bilayer MoS2 used as photoreceptors can be customized via the transfer technique using patternable paraffin, where the twist angle and fold-line could be controlled. The photoluminescence (PL) intensity is 3.7 times higher at a twist angle of 29° compared to that at 0°, showing a monotonically decreasing indirect bandgap. Through tunable interlayer carrier transport, photoreceptors fabricated using folded bilayer MoS2 at different twist angles demonstrate gradient response time, enabling the photostimulated-motion artificial reflex arc for multiaction responses. They are transformed to digital command flow and studied via machine learning to control the gestures of a robotic hand, showing a prototype of photostimulated gradient-responsive artificial reflex arcs for the first time. This work provides a unique idea for developing intelligent soft robots and next-generation human-computer interfaces.
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Affiliation(s)
- Weifeng Zhang
- Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing, 100875, P. R. China
| | - Mengwei Wu
- College of Engineering, Peking University, Beijing, 100871, China
| | - Yan Zhang
- Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing, 100875, P. R. China
| | - Hongyi Yan
- Department of Physics, Beijing Normal University, Beijing, 100875, P. R. China
| | - Yangjin Lee
- Center for Nanomedicine, Institute for Basic Science, Seoul, 03722, South Korea
- Department of Physics, Yonsei University, Seoul, 03722, South Korea
| | - Zihan Zhao
- Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing, 100875, P. R. China
| | - He Hao
- Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing, 100875, P. R. China
| | - Xiaohu Shi
- Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing, 100875, P. R. China
| | - Zhaoxian Zhang
- College of Design and Engineering, National University of Singapore, 9 Engineering Drive 1, #07-26, EA, Singapore, 117575, Singapore
| | - Kwanpyo Kim
- Center for Nanomedicine, Institute for Basic Science, Seoul, 03722, South Korea
- Department of Physics, Yonsei University, Seoul, 03722, South Korea
| | - Nan Liu
- Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing, 100875, P. R. China
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