Are Microwave Induced Zero Resistance States Necessarily Static?

TL;DR

This paper investigates how inhomogeneities in Hall conductivity can lead to dynamic, time-dependent domain patterns in microwave-induced zero resistance states in 2D electron systems, challenging the assumption of static states.

Contribution

It introduces a model showing that zero resistance states can be non-static and time-dependent due to inhomogeneities, supported by simulations and eigenmode analysis.

Findings

Time-periodic non-equilibrium solutions in annular geometries.

Existence of nonstationary states in intermediate inhomogeneity regimes.

Eigenmode analysis estimates the periods of dynamic solutions.

Abstract

We study the effect of inhomogeneities in Hall conductivity on the nature of the Zero Resistance States seen in the microwave irradiated two-dimensional electron systems in weak perpendicular magnetic fields, and we show that time-dependent domain patterns may emerge in some situations. For an annular Corbino geometry, with an equilibrium charge density that varies linearly with radius, we find a time-periodic non-equilibrium solution, which might be detected by a charge sensor, such as an SET. For a model on a torus, in addition to static domain patterns seen at high and low values of the equilibrium charge inhomogeneity, we find that, in the intermediate regime, a variety of nonstationary states can also exist. We catalog the possibilities we have seen in our simulations. Within a particular phenomenological model, we show that linearizing the nonlinear charge continuity equation about a particularly simple domain wall configuration and analyzing the eigenmodes allows us to estimate the periods of the solutions to the full nonlinear equation.