Quantum Hall to Insulator Transition in the Bilayer Quantum Hall Ferromagnet

TL;DR

This paper investigates a novel phase transition in a bilayer quantum Hall ferromagnet at filling fraction 1, where disorder induces a superfluid-insulator transition of spinons while maintaining ferromagnetic order, revealing emergent gauge phenomena.

Contribution

It introduces a new disorder-driven phase transition involving Higgs and Coulomb phases in the bilayer quantum Hall ferromagnet, with detailed analysis of physical consequences.

Findings

Bosonic spinons undergo superfluid-insulator transition

Emergence of U(1) photon in the Mott insulator

Implications for charge and tunneling conductance

Abstract

We describe a new phase transition of the bilayer quantum Hall ferromagnet at filling fraction $\nu = 1$. In the presence of static disorder (modeled by a periodic potential), bosonic $S=1/2$ spinons can undergo a superfluid-insulator transition while preserving the ferromagnetic order. The Mott insulating phase has an emergent U(1) photon, and the transition is between Higgs and Coulomb phases of this photon. Physical consequences for charge and counterflow conductivity, and for interlayer tunneling conductance in the presence of quenched disorder are discussed.