Microwave induced magnetoresistance oscillations at the subharmonics of the cyclotron resonance

TL;DR

This paper investigates microwave-induced magnetoresistance oscillations at subharmonics of the cyclotron resonance in a 2D electron system, explaining the phenomena with a non-equilibrium energy distribution model and identifying a frequency threshold for their disappearance.

Contribution

It demonstrates that subharmonic oscillations can be explained without multi-photon absorption, introducing a threshold frequency for their occurrence.

Findings

Subharmonic oscillations occur at n=2, 3, 4.

Oscillations are explained by a non-equilibrium distribution function.

A frequency threshold exists above which oscillations vanish.

Abstract

The magnetoresistance oscillations, which occur in a two-dimensional electron system exposed to strong microwave radiation when the microwave frequency $\omega$ coincides with the n-th subharmonic of the cyclotron frequency $\omega_c$ have been investigated for n = 2, 3 and 4. It is shown that these subharmonic features can be explained within a non-equilibrium energy distribution function picture without invoking multi-photon absorption processes. The existence of a frequency threshold above which such oscillations disappear lends further support to this explanation.