Transport properties of \nu=1 quantum Hall bilayers. Phenomenological description

TL;DR

This paper introduces a phenomenological model for quantum Hall bilayers at =1, explaining transport phenomena like counterflow and drag through vortex excitations and their temperature-dependent dynamics.

Contribution

It presents a novel phenomenological framework incorporating vortex excitations and defect areas to describe transport properties in quantum Hall bilayers at =1.

Findings

Vortex excitations cause decay of exciton supercurrent.

Temperature-dependent resistivities are explained by viscous forces on vortices.

Defect areas can lead to negative longitudinal drag resistivity.

Abstract

We propose a phenomenological model that describes counterflow and drag experiments with quantum Hall bilayers in a \nu_T=1 state. We consider the system consisting of statistically distributed areas with local total filling factors \nu_{T1}>1 and \nu_{T2}<1. The excess or deficit of electrons in a given area results in an appearance of vortex excitations. The vortices in quantum Hall bilayers are charged. They are responsible for a decay of the exciton supercurrent, and, at the same time, contribute to the conductivity directly. The experimental temperature dependence of the counterflow and drive resistivities is described under accounting viscous forces applied to vortices that are the exponentially increase functions of the inverse temperature. The presence of defect areas where the interlayer phase coherence is destroyed completely can result in an essential negative longitudinal drag resistivity as well as in a counterflow Hall resistivity.