Spin Bose Glass Phase in Bilayer Quantum Hall Systems at $\nu=2$

TL;DR

This paper introduces an effective spin theory for $ u=2$ bilayer quantum Hall systems, predicting a novel spin Bose glass phase with unique magnetic properties, supported by agreement with microscopic calculations.

Contribution

The paper develops a new effective spin model that accurately describes magnetic phases and predicts a previously unknown spin Bose glass phase in bilayer quantum Hall systems.

Findings

Agreement with Hartree-Fock calculations in disorder-free systems

Prediction of a spin Bose glass phase with unique magnetic properties

Identification of a universal longitudinal spin conductance at phase transition

Abstract

We develop an effective spin theory to describe magnetic properties of the $\nu=2$ Quantum Hall bilayer systems. In the absence of disorder this theory gives quantitative agreement with the results of microscopic Hartree-Fock calculations, and for finite disorder it predicts the existence of a novel spin Bose glass phase. The Bose glass is characterized by the presence of domains of canted antiferromagnetic phase with zero average antiferromagnetic order and short range mean antiferromagnetic correlations. It has infinite antiferromagnetic transverse susceptibility, finite longitudinal spin susceptibility and specific heat linear in temperature. Transition from the canted antiferromagnet phase to the spin Bose glass phase is characterized by a universal value of the longitudinal spin conductance.