Evidence for effective mass reduction in GaAs/AlGaAs quantum wells

TL;DR

This study uses microwave photoresistance measurements in high mobility GaAs/AlGaAs quantum wells to find a significant reduction in effective mass, indicating strong electron-electron interactions affecting electron dynamics.

Contribution

It provides experimental evidence of effective mass reduction in GaAs/AlGaAs quantum wells, highlighting electron-electron interactions via microwave photoresistance.

Findings

Effective mass is about 12% lower than the band mass in GaAs.

Microwave-induced resistance oscillations reveal mass reduction.

Magnetoplasmon dispersion shows effective mass close to the band mass.

Abstract

We have performed microwave photoresistance measurements in high mobility GaAs/AlGaAs quantum wells and investigated the value of the effective mass. Surprisingly, the effective mass, obtained from the period of microwave-induced resistance oscillations, is found to be about 12% lower than the band mass in GaAs, $\mb$. This finding provides strong evidence for electron-electron interactions which can be probed by microwave photoresistance in very high Landau levels. In contrast, the measured magnetoplasmon dispersion revealed an effective mass which is close to $\mb$, in accord with previous studies.