Magnetoconductivity oscillations induced by intersubband excitation in a degenerate 2D electron gas

TL;DR

This paper theoretically investigates how nonequilibrium populations of excited subbands in a degenerate 2D electron gas induce magnetoconductivity oscillations and negative conductivity, revealing new oscillation shapes and effects from small electron transfers.

Contribution

It introduces a theoretical model showing that nonequilibrium subband populations cause unique conductivity oscillations and negative conductivity in a 2D electron system, extending understanding beyond traditional effects.

Findings

Sign-changing oscillations with distinct shapes are possible.

Small electron transfers to excited subbands can cause negative conductivity.

Oscillations occur beyond standard Shubnikov-de Haas conditions.

Abstract

Magnetoconductivity oscillations and absolute negative conductivity induced by nonequilibrium populations of excited subbands in a degenerate multisubband two-dimensional electron system are studied theoretically. The displacement from equilibrium, which can be caused by resonant microwave excitation or by any other reason, is assumed to be such that electron distributions can no longer be described by a single Fermi level. In this case, in addition to the well-known conductivity peaks occurring at the Shubnikov-de Haas conditions and small peaks of normal intersubband scattering, sign-changing oscillations with a different shape are shown to be possible. We found also that even a small fraction of electrons transferred to the excited subband can lead to negative conductivity effects.