A magnetic resonance in high-frequency viscosity of two-dimensional electrons

TL;DR

This paper develops a theory for high-frequency magnetotransport in viscous 2D electron fluids, predicting a resonance at twice the cyclotron frequency that explains observed peaks in photoresistance and photovoltage.

Contribution

It introduces a novel theoretical framework accounting for time-dependent viscosity effects and predicts a unique resonance in shear viscosity at twice the cyclotron frequency.

Findings

Resonance at twice the cyclotron frequency in shear viscosity.

Resonance influences plasmon damping and photoresponse features.

Supports the viscous electron fluid hypothesis in high-quality GaAs quantum wells.

Abstract

Two-dimensional (2D) electrons in high-quality nanostructures at low temperatures can form a viscous fluid. We develop a theory of high-frequency magnetotransport in such fluid. The time dispersion of viscosity should be taken into account at the frequencies about and above the rate of electron-electron collisions. We show that the shear viscosity coefficients as functions of magnetic field and frequency have the only resonance at the frequency equal to the doubled cyclotron frequency. We demonstrate that such resonance manifests itself in the plasmon damping. Apparently, the predicted resonance is also responsible for the peaks and features in photoresistance and photovoltage, recently observed on the best-quality GaAs quantum wells. The last fact should considered as an important evidence of forming a viscous electron fluid in such structures.