Microwave absorption/reflection and magneto-transport experiments on high-mobility electron gas

TL;DR

This study investigates microwave absorption and magneto-transport in high-mobility 2D electron gases, revealing complex plasma and electrodynamic effects influencing MIROs, with experimental results aligning with existing theoretical models.

Contribution

It provides new insights into the electrodynamic effects and plasma phenomena affecting MIROs in high-mobility electron gases, expanding understanding beyond simple resonance absorption.

Findings

Broad cyclotron resonance line observed due to high conductivity.

Reflection experiments show oscillation patterns linked to plasma effects.

Experimental results agree with the photo-assisted scattering model.

Abstract

We have performed simultaneous measurements of microwave absorption/reflection and magneto-transport characteristics of a high mobility two-dimensional electrons in GaAs/AlGaAs heterostructure in regime of Microwave-Induced Resistance Oscillations (MIROs). It is shown that the electrodynamic aspect of the problem is important in these experiments. In the absorption experiments a broad cyclotron resonance line was observed due to a large reflection from the highly conductive electron gas. There were no additional features observed related to absorption at harmonics of the cyclotron resonance. In near-field reflection experiments a very different oscillation pattern was revealed when compared to MIROs. The oscillation pattern observed in the reflection experiments is probably due to plasma effects occurring in a finite-size sample. The whole microscopic picture of MIROs is more complicated than simply a resonant absorption at harmonics of the cyclotron resonance. Nevertheless, the experimental observations are in good agreement with the model by Ryzhii et al. involving the photo-assisted scattering in the presence of a crossed magnetic field and dc bias. The observed damping factor of MIROs may be attributed to a change in the electron mobility as a function of temperature.