Spin symmetry breaking in bilayer quantum Hall systems

TL;DR

This paper predicts a broad class of spin symmetry breaking states in bilayer quantum Hall systems, extending known phases, and develops a theoretical framework to describe their excitations and properties.

Contribution

It introduces generalized Halperin wave functions for new spin symmetry broken states and formulates a Chern-Simons theory to analyze their excitations.

Findings

Existence of Goldstone mode in neutral excitations

Charged excitations are bimerons with tunable charge

Generalization of canted antiferromagnetic phase to fractional fillings

Abstract

Based on the construction of generalized Halperin wave functions, we predict the possible existence of a large class of broken spin symmetry states in bilayer quantum Hall structures, generalizing the recently suggested canted antiferromgnetic phase to many fractional fillings. We develop the appropriate Chern-Simons theory, and establish explicitly that the low-lying neutral excitation is a Goldstone mode and that the charged excitations are bimerons with continuously tunable (through the canted antiferromagnetic order parameter) electric charge on the individual merons.