Graphene’s non-equilibrium fermions reveal Doppler-shifted magnetophonon resonances accompanied by Mach supersonic and Landau velocity effects

Greenaway, M. T.; Kumaravadivel, P.; Wengraf, J.; Ponomarenko, L. A.; Berdyugin, A. I.; Li, J.; Edgar, J. H.; Kumar, R. Krishna; Geim, A. K.; Eaves, L.

Abstract

Oscillatory 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.

Citation

Greenaway, M. T., Kumaravadivel, P., Wengraf, J., Ponomarenko, L. A., Berdyugin, A. I., Li, J., …Eaves, L. (2021). Graphene’s non-equilibrium fermions reveal Doppler-shifted magnetophonon resonances accompanied by Mach supersonic and Landau velocity effects. Nature Communications, 12, 1-6. https://doi.org/10.1038/s41467-021-26663-4

• Journal Article Type: Article
• Acceptance Date: Oct 15, 2021
• Online Publication Date: Nov 4, 2021
• Publication Date: Nov 4, 2021
• Deposit Date: Oct 20, 2021
• Publicly Available Date: Nov 8, 2021
• Journal: Nature Communications
• Electronic ISSN: 2041-1723
• Publisher: Nature Publishing Group
• Peer Reviewed: Peer Reviewed
• Volume: 12
• Article Number: 6392
• Pages: 1-6
• DOI: https://doi.org/10.1038/s41467-021-26663-4
• Keywords: General Physics and Astronomy; General Biochemistry, Genetics and Molecular Biology; General Chemistry
• Public URL: https://nottingham-repository.worktribe.com/output/6505233
• Publisher URL: https://www.nature.com/articles/s41467-021-26663-4