Symmetry breaking as the origin of zero-differential resistance states of a 2DEG in strong magnetic fields

TL;DR

This paper models the nonlinear transport in 2DEG under strong magnetic fields, predicting symmetry breaking and a novel phase with persistent current, linked to a quantum phase transition at high magnetic fields.

Contribution

It introduces an analytical model for zero-resistance states in 2DEG, revealing symmetry breaking and a new phase with permanent current at high magnetic fields.

Findings

Prediction of negative differential resistivity states

Derivation of an energy functional for the system

Identification of a quantum phase transition with symmetry breaking

Abstract

Zero resistance differential states have been observed in two-dimensional electron gases (2DEG) subject to a magnetic field and a strong dc current. In a recent work we presented a model to describe the nonlinear transport regime of this phenomenon. From the analysis of the differential resistivity and the longitudinal voltage we predicted the formation of negative differential resistivity states, although these states are known to be unstable. Based on our model, we derive an analytical approximated expression for the Voltage-Current characteristics, that captures the main elements of the problem. The result allow us to construct an energy functional for the system. In the zero temperature limit, the system presents a quantum phase transition, with the control parameter given by the magnetic field. It is noted that above a threshold value ($B>B_{th}$), the symmetry is spontaneously broken. At sufficiently high magnetic field and low temperature the model predicts a phase with a non-vanishing permanent current; this is a novel phase that has not been observed so far.