Spin excitations in two-dimensional electron gas, their relaxation, photoexcitation, and detection methods, and the role of Coulomb correlations

We discuss spin excitations in a degenerate 2D electron gas in a perpendicular quantizing magnetic field: spin-wave and 'Goldstone' excitons in a quantum Hall ferromagnetic (filling factor ν = 1), and spin-cyclotron excitons in a quantum Hall insulator (ν = 2). The latter exhibit record-se...

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Bibliographic Details
Published in:Physics Uspekhi 2019-09, Vol.62 (9), p.865-891
Main Authors: Kulik, L V, Gorbunov, A V, Dickmann, S M, Timofeev, V B
Format: Article
Language:English
Subjects:
collective excitations
Condensates
Counting
Cyclotrons
Electron gas
Electron spin
Electrons
Excitons
Fermions
Ferromagnetism
magnetoexcitons
magnetofermionic condensate
Photoexcitation
quantum Hall ferromagnet
quantum Hall insulator
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Summary:We discuss spin excitations in a degenerate 2D electron gas in a perpendicular quantizing magnetic field: spin-wave and 'Goldstone' excitons in a quantum Hall ferromagnetic (filling factor ν = 1), and spin-cyclotron excitons in a quantum Hall insulator (ν = 2). The latter exhibit record-setting long lifetimes, up to 1 ms, owing to which a transition to a basically new collective state, a magnetofermionic condensate, is observable at temperatures T < 1 K. The condensate's properties may be explained in terms of a coherent state being formed due to the emergence of a dense ensemble of photoexcited long-lived spin-cyclotron excitons obeying Bose statistics in a nonequilibrium system of 2D fermions.
ISSN:1063-7869
1468-4780
DOI:10.3367/UFNe.2018.10.038463