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Nathawat J, Mansaray I, Sakanashi K, Wada N, Randle MD, Yin S, He K, Arabchigavkani N, Dixit R, Barut B, Zhao M, Ramamoorthy H, Somphonsane R, Kim GH, Watanabe K, Taniguchi T, Aoki N, Han JE, Bird JP. Signatures of hot carriers and hot phonons in the re-entrant metallic and semiconducting states of Moiré-gapped graphene. Nat Commun 2023; 14:1507. [PMID: 36932096 PMCID: PMC10023744 DOI: 10.1038/s41467-023-37292-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 03/09/2023] [Indexed: 03/19/2023] Open
Abstract
Stacking of graphene with hexagonal boron nitride (h-BN) can dramatically modify its bands from their usual linear form, opening a series of narrow minigaps that are separated by wider minibands. While the resulting spectrum offers strong potential for use in functional (opto)electronic devices, a proper understanding of the dynamics of hot carriers in these bands is a prerequisite for such applications. In this work, we therefore apply a strategy of rapid electrical pulsing to drive carriers in graphene/h-BN heterostructures deep into the dissipative limit of strong electron-phonon coupling. By using electrical gating to move the chemical potential through the "Moiré bands", we demonstrate a cyclical evolution between metallic and semiconducting states. This behavior is captured in a self-consistent model of non-equilibrium transport that considers the competition of electrically driven inter-band tunneling and hot-carrier scattering by strongly non-equilibrium phonons. Overall, our results demonstrate how a treatment of the dynamics of both hot carriers and hot phonons is essential to understanding the properties of functional graphene superlattices.
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Affiliation(s)
- Jubin Nathawat
- Department of Electrical Engineering, University at Buffalo, the State University of New York, Buffalo, NY, 14260, USA
| | - Ishiaka Mansaray
- Department of Physics, University at Buffalo, the State University of New York, Buffalo, NY, 14260, USA
| | - Kohei Sakanashi
- Department of Materials Science, Chiba University, Inage-ku, Chiba, 263-8522, Japan
| | - Naoto Wada
- Department of Materials Science, Chiba University, Inage-ku, Chiba, 263-8522, Japan
| | - Michael D Randle
- Department of Electrical Engineering, University at Buffalo, the State University of New York, Buffalo, NY, 14260, USA
| | - Shenchu Yin
- Department of Electrical Engineering, University at Buffalo, the State University of New York, Buffalo, NY, 14260, USA
| | - Keke He
- Department of Electrical Engineering, University at Buffalo, the State University of New York, Buffalo, NY, 14260, USA
| | - Nargess Arabchigavkani
- Department of Electrical Engineering, University at Buffalo, the State University of New York, Buffalo, NY, 14260, USA
| | - Ripudaman Dixit
- Department of Electrical Engineering, University at Buffalo, the State University of New York, Buffalo, NY, 14260, USA
| | - Bilal Barut
- Department of Physics, University at Buffalo, the State University of New York, Buffalo, NY, 14260, USA
| | - Miao Zhao
- High-Frequency High-Voltage Device and Integrated Circuits Center, Institute of Microelectronics of Chinese Academy of Sciences, 3 Beitucheng West Road, Chaoyang District, Beijing, 100029, PR China
| | - Harihara Ramamoorthy
- Department of Electronics Engineering, Faculty of Engineering, King Mongkut's Institute of Technology Ladkrabang, Bangkok, 10520, Thailand
| | - Ratchanok Somphonsane
- Department of Physics, Faculty of Science, King Mongkut's Institute of Technology Ladkrabang, Bangkok, 10520, Thailand
| | - Gil-Ho Kim
- School of Electronic and Electrical Engineering and Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, 16419, Korea
| | - Kenji Watanabe
- Advanced Materials Laboratory, National Institute for Materials Science, Tsukuba, 305-0044, Japan
| | - Takashi Taniguchi
- Advanced Materials Laboratory, National Institute for Materials Science, Tsukuba, 305-0044, Japan
| | - Nobuyuki Aoki
- Department of Materials Science, Chiba University, Inage-ku, Chiba, 263-8522, Japan
| | - Jong E Han
- Department of Physics, University at Buffalo, the State University of New York, Buffalo, NY, 14260, USA.
| | - Jonathan P Bird
- Department of Electrical Engineering, University at Buffalo, the State University of New York, Buffalo, NY, 14260, USA. .,Department of Physics, University at Buffalo, the State University of New York, Buffalo, NY, 14260, USA.
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Weng Q, Komiyama S, Yang L, An Z, Chen P, Biehs SA, Kajihara Y, Lu W. Imaging of nonlocal hot-electron energy dissipation via shot noise. Science 2018; 360:775-778. [PMID: 29599192 DOI: 10.1126/science.aam9991] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 10/19/2017] [Accepted: 03/12/2018] [Indexed: 11/02/2022]
Abstract
In modern microelectronic devices, hot electrons accelerate, scatter, and dissipate energy in nanoscale dimensions. Despite recent progress in nanothermometry, direct real-space mapping of hot-electron energy dissipation is challenging because existing techniques are restricted to probing the lattice rather than the electrons. We realize electronic nanothermometry by measuring local current fluctuations, or shot noise, associated with ultrafast hot-electron kinetic processes (~21 terahertz). Exploiting a scanning and contact-free tungsten tip as a local noise probe, we directly visualize hot-electron distributions before their thermal equilibration with the host gallium arsenide/aluminium gallium arsenide crystal lattice. With nanoconstriction devices, we reveal unexpected nonlocal energy dissipation at room temperature, which is reminiscent of ballistic transport of low-temperature quantum conductors.
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Affiliation(s)
- Qianchun Weng
- National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, The Chinese Academy of Sciences, Shanghai 200083, PR China.,Institute of Industrial Science, The University of Tokyo, Komaba 4-6-1, Meguro-ku, Tokyo, 153-8505, Japan
| | - Susumu Komiyama
- National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, The Chinese Academy of Sciences, Shanghai 200083, PR China.,Department of Basic Science, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo, 153-8902, Japan
| | - Le Yang
- State Key Laboratory of Surface Physics, Institute for Nanoelectronic Devices and Quantum Computing, and Key Laboratory of Micro and Nano Photonics Structures (Ministry of Education), Department of Physics, Fudan University, Shanghai 200433, PR China
| | - Zhenghua An
- State Key Laboratory of Surface Physics, Institute for Nanoelectronic Devices and Quantum Computing, and Key Laboratory of Micro and Nano Photonics Structures (Ministry of Education), Department of Physics, Fudan University, Shanghai 200433, PR China. .,Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, PR China
| | - Pingping Chen
- National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, The Chinese Academy of Sciences, Shanghai 200083, PR China
| | - Svend-Age Biehs
- Institut für Physik, Carl von Ossietzky Universität, D-26111 Oldenburg, Germany
| | - Yusuke Kajihara
- Institute of Industrial Science, The University of Tokyo, Komaba 4-6-1, Meguro-ku, Tokyo, 153-8505, Japan
| | - Wei Lu
- National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, The Chinese Academy of Sciences, Shanghai 200083, PR China.
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Rotter I, Bird JP. A review of progress in the physics of open quantum systems: theory and experiment. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2015; 78:114001. [PMID: 26510115 DOI: 10.1088/0034-4885/78/11/114001] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This report on progress explores recent advances in our theoretical and experimental understanding of the physics of open quantum systems (OQSs). The study of such systems represents a core problem in modern physics that has evolved to assume an unprecedented interdisciplinary character. OQSs consist of some localized, microscopic, region that is coupled to an external environment by means of an appropriate interaction. Examples of such systems may be found in numerous areas of physics, including atomic and nuclear physics, photonics, biophysics, and mesoscopic physics. It is the latter area that provides the main focus of this review, an emphasis that is driven by the capacity that exists to subject mesoscopic devices to unprecedented control. We thus provide a detailed discussion of the behavior of mesoscopic devices (and other OQSs) in terms of the projection-operator formalism, according to which the system under study is considered to be comprised of a localized region (Q), embedded into a well-defined environment (P) of scattering wavefunctions (with Q + P = 1). The Q subspace must be treated using the concepts of non-Hermitian physics, and of particular interest here is: the capacity of the environment to mediate a coupling between the different states of Q; the role played by the presence of exceptional points (EPs) in the spectra of OQSs; the influence of EPs on the rigidity of the wavefunction phases, and; the ability of EPs to initiate a dynamical phase transition (DPT). EPs are singular points in the continuum, at which two resonance states coalesce, that is where they exhibit a non-avoided crossing. DPTs occur when the quantum dynamics of the open system causes transitions between non-analytically connected states, as a function of some external control parameter. Much like conventional phase transitions, the behavior of the system on one side of the DPT does not serve as a reliable indicator of that on the other. In addition to discussing experiments on mesoscopic quantum point contacts that provide evidence of the environmentally-mediated coupling of quantum states, we also review manifestations of DPTs in mesoscopic devices and other systems. These experiments include observations of resonance-trapping behavior in microwave cavities and open quantum dots, phase lapses in tunneling through single-electron transistors, and spin swapping in atomic ensembles. Other possible manifestations of this phenomenon are presented, including various superradiant phenomena in low-dimensional semiconductors. From these discussions a generic picture of OQSs emerges in which the environmentally-mediated coupling between different quantum states plays a critical role in governing the system behavior. The ability to control or manipulate this interaction may even lead to new applications in photonics and electronics.
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Affiliation(s)
- I Rotter
- Max Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany
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