Microwave-resonance-induced magnetooscillations and vanishing resistance states in multisubband two-dimensional electron systems

TL;DR

This paper investigates microwave-induced magnetooscillations and zero-resistance states in multisubband 2D electron systems on liquid helium, revealing a new negative conductivity mechanism and matching experimental data.

Contribution

It introduces a novel negative linear response conductivity mechanism in multisubband 2D electron systems under microwave irradiation, considering two types of scatterers and electron heating effects.

Findings

Sign-changing correction to conductivity appears near inter-subband resonance.

Magnetooscillations of electron temperature enhance conductivity correction.

Calculated oscillation line shapes agree with experimental observations.

Abstract

The dc magnetoconductivity of the multisubband two-dimensional electron system formed on the liquid helium surface in the presence of resonant microwave irradiation is described, and a new mechanism of the negative linear response conductivity is studied using the self-consistent Born approximation. Two kinds of scatterers (vapor atoms and capillary wave quanta) are considered. Besides a conductivity modulation expected near the points, where the excitation frequency for inter-subband transitions is commensurate with the cyclotron frequency, a sign-changing correction to the linear conductivity is shown to appear for usual quasi-elastic inter-subband scattering, if the collision broadening of Landau levels is much smaller than thermal energy. The decay heating of the electron system near the commensurability points leads to magnetooscillations of electron temperature, which are shown to increase the importance of the sign-changing correction. The line shape of magnetoconductivity oscillations calculated for wide ranges of temperature and magnetic field is in a good accordance with experimental observations.