Coherence Network in the Quantum Hall Bilayer

TL;DR

This paper proposes that the near-dissipationless transport in quantum Hall bilayers can be explained by a disorder-induced coherence network, modeled as a vortex liquid with specific temperature-dependent transport properties.

Contribution

It introduces the concept of a coherence network induced by disorder in quantum Hall bilayers and models it as a vortex liquid to explain experimental observations.

Findings

Power law temperature dependence of tunneling resistance.

Thermally activated vortex hops control counterflow resistance.

System behavior is well-described by a vortex liquid model.

Abstract

Recent experiments on quantum Hall bilayers near total filling factor 1 have demonstrated that they support an ``imperfect'' two-dimensional superfluidity, in which there is nearly dissipationless transport at non-vanishing temperature observed both in counterflow resistance and interlayer tunneling. We argue that this behavior may be understood in terms of a {\it coherence network} induced in the bilayer by disorder, in which an incompressible, coherent state exists in narrow regions separating puddles of dense vortex-antivortex pairs. A renormalization group analysis shows that it is appropriate to describe the system as a vortex liquid. We demonstrate that the dynamics of the nodes of the network leads to a power law temperature dependence of the tunneling resistance, whereas thermally activated hops of vortices across the links control the counterflow resistance.