Sergey M. Dickmann
Received 25 October 2018; revised 2 April 2019; accepted 21 June
2019
In connection with recent studies of
extremely long-living spin-cyclotron excitations that are
actually magnetoexcitons in the quantum Hall electron gas, we
discuss the contribution to light absorption related to the
presence of a magnetoexcitonic ensemble in this purely
electronic system. The distribution of magnetoexcitons in an
‘incoherent’ phase, as well as absorption of light, is
determined by a smooth random potential inevitably present in
a quantum well. Since weakly interacting excitations have to
obey the Bose–Einstein statistics, one may expect the
appearance of a coherent phase where all magnetoexcitons are
in the same state. The absorption of light is still determined
by disorder in the system, but it turns out to be about an
order of magnitude higher. A comparative analysis is made of
both incoherent and coherent cases. The condition for
coherent–incoherent phase transition is discussed. It is
expected to be strongly related to long-distance
inter-excitonic correlations. The latter are accounted in
terms of virial correction (i.e. depending on magnetoexciton
concentration) for the single magnetoexciton energy found
within the approximation of a slightly non-ideal gas.
Keywords: two-dimensional electron gas, quantum well,
magnetic field, optical absorption, resonant Rayleigh
reflection, magnetoexciton, cyclotron spin-flip excitation,
Bose–Einstein condensation
PACS: 73.21.Fg, 73.43.Lp, 78.67.De
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