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Graphene’s non-equilibrium fermions reveal Doppler-shifted magnetophonon resonances accompanied by Mach supersonic and Landau velocity effects
journal contribution
posted on 2021-11-22, 11:57 authored by Mark GreenawayMark Greenaway, P Kumaravadivel, J Wengraf, LA Ponomarenko, AI Berdyugin, J Li, JH Edgar, R Krishna Kumar, AK Geim, L EavesOscillatory magnetoresistance measurements on graphene have revealed a wealth of novel physics. These phenomena are typically studied at low currents. At high currents, electrons are driven far from equilibrium with the atomic lattice vibrations so that their kinetic energy can exceed the thermal energy of the phonons. Here, we report three non-equilibrium phenomena in monolayer graphene at high currents: (i) a “Doppler-like” shift and splitting of the frequencies of the transverse acoustic (TA) phonons emitted when the electrons undergo inter-Landau level (LL) transitions; (ii) an intra-LL Mach effect with the emission of TA phonons when the electrons approach supersonic speed, and (iii) the onset of elastic inter-LL transitions at a critical carrier drift velocity, analogous to the superfluid Landau velocity. All three quantum phenomena can be unified in a single resonance equation. They offer avenues for research on out-of-equilibrium phenomena in other two-dimensional fermion systems.
Funding
Quantum dynamics of electrons in emerging van der Waals devices
Engineering and Physical Sciences Research Council
Find out more...Designing and exploring new quantum materials based on Fermi surface topological transitions
Engineering and Physical Sciences Research Council
Find out more...Lloyd’s Register Foundation
Office of Naval Research (award no. N00014-20-1-2474)
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- Science
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- Physics
Published in
Nature CommunicationsVolume
12Publisher
Springer NatureVersion
- VoR (Version of Record)
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© The AuthorsPublisher statement
This is an Open Access Article. It is published by Springer Nature under the Creative Commons Attribution 4.0 International Licence (CC BY 4.0). Full details of this licence are available at: https://creativecommons.org/licenses/by/4.0/Acceptance date
2021-10-15Publication date
2021-11-04Copyright date
2021eISSN
2041-1723Publisher version
Language
- en
Depositor
Dr Mark Greenaway. Deposit date: 21 September 2021Article number
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