Low-frequency conductivity of a non-degenerate 2D electron liquid in strong magnetic fields

TL;DR

This paper investigates the low-frequency conductivity behavior of a nondegenerate 2D electron liquid in strong magnetic fields, revealing how disorder and electron vibrations influence the shape and width of the conductivity peak.

Contribution

It provides a detailed analysis of the conductivity peak shape and width, considering the effects of disorder correlation length and electron vibrations, including the impact of rare charged traps.

Findings

Conductivity peak shape depends on disorder correlation length and electron vibrations.

Peak width is determined by electron motion over the disorder scale or magnetic length.

Rare charged traps influence the conductivity spectrum through combined short- and long-time electron dynamics.

Abstract

We study the conductivity of a nondegenerate 2D electron liquid in a quantizing magnetic field for frequencies well below the cyclotron frequency. The conductivity is formed by electron transitions in which the energy of a photon goes to the interaction energy of the many-electron system, whereas the involved momentum is transferred to quenched disorder. The conductivity peak is non-Lorentzian. Its shape depends on the relation between the correlation length r_c of the disorder potential and the typical amplitude delta_f of vibrations of the electrons about their quasi-equilibrium positions in the liquid. The width of the peak is determined by the reciprocal time it takes an electron to move over r_c (or the magnetic length l, for r_c< l). In turn, this time is determined by vibrational or diffusive motion, depending on the ratio r_c/delta_f. We analyze the tail of the conductivity peak for short-range disorder. It is formed by multiple collisions with the disorder potential. We also analyze scattering by rare negatively charged traps and show that the conductivity spectrum in this case depends on both short- and long-time electron dynamics.