Deconfinement and Dissipation in Quantum Hall "Josephson" Tunneling

TL;DR

This paper investigates the zero-bias tunneling resonance in quantum Hall bilayer systems using numerical simulations of a classical XY model, revealing disorder-induced string states that cause large dissipation, aligning with experimental observations.

Contribution

It introduces a novel string glass state in the XY model with disorder, explaining dissipation in quantum Hall tunneling phenomena.

Findings

Disorder nucleates strings of overturned spins with vortices at endpoints.

String glass state supports low energy excitations causing large dissipation.

In-plane magnetic field effects are discussed.

Abstract

The zero-bias tunneling resonance in quantum Hall bilayer systems is investigated via numerical simulations of the classical two dimensional XY model with a symmetry-breaking field. Disorder is included in the model, and is shown to nucleate strings of overturned spins proliferated through the system, with unpaired vortices and antivortices at their endpoints. This string glass state supports low energy excitations which lead to anomalously large dissipation in tunneling, as observed in experiment. The effect of an in-plane magnetic field is discussed.