Theory of Activated Transport in Bilayer Quantum Hall Systems

TL;DR

This paper investigates the transport behavior of disordered bilayer quantum Hall systems at total filling factor one, revealing how meron dynamics and interactions lead to layer-specific dissipation and multiple activation energies.

Contribution

It introduces a combined Hartree-Fock and bosonic Chern-Simons theoretical framework to explain layer-dependent dissipation and activation energies in disordered bilayer quantum Hall systems.

Findings

Multiple activation energies arise due to disorder-induced meron unbinding.

Current in one layer causes dissipation only in the drive layer.

Different temperature dependencies for drag and drive layers match experimental observations.

Abstract

We analyze the transport properties of bilayer quantum Hall systems at total filling factor $\nu=1$ in drag geometries as a function of interlayer bias, in the limit where the disorder is sufficiently strong to unbind meron-antimeron pairs, the charged topological defects of the system. We compute the typical energy barrier for these objects to cross incompressible regions within the disordered system using a Hartree-Fock approach, and show how this leads to multiple activation energies when the system is biased. We then demonstrate using a bosonic Chern-Simons theory that in drag geometries, current in a single layer directly leads to forces on only two of the four types of merons, inducing dissipation only in the drive layer. Dissipation in the drag layer results from interactions among the merons, resulting in very different temperature dependences for the drag and drive layers, in qualitative agreement with experiment.