Microwave-Induced Oscillations in the Magnetocapacitance: Direct Evidence for Non-equilibrium Occupation of Electronic States

TL;DR

This paper provides direct experimental evidence that microwave radiation causes non-equilibrium electron distributions in a two-dimensional system, leading to magnetocapacitance oscillations linked to Landau quantization.

Contribution

It demonstrates that microwave-induced magnetocapacitance oscillations are caused by oscillating electron distribution functions, confirming a quantum mechanism for resistance oscillations.

Findings

Microwave radiation induces magnetocapacitance oscillations.

Oscillations are due to non-equilibrium electron distributions.

Results support Landau quantization as the underlying mechanism.

Abstract

In a two-dimensional electron system, microwave radiation may induce giant resistance oscillations. Their origin has been debated controversially and numerous mechanisms based on very different physical phenomena have been invoked. However none of them have been unambiguously experimentally identified, since they produce similar effects in transport studies. The capacitance of a two-subband system is sensitive to a redistribution of electrons over energy states, since it entails a shift of the electron charge perpendicular to the plane. In such a system microwave induced magnetocapacitance oscillations have been observed. They can only be accounted for by an electron distribution function oscillating with energy due to Landau quantization, one of the quantum mechanisms proposed for the resistance oscillations.