A bosonization approach for bilayer quantum Hall systems at \nu_T = 1

TL;DR

This paper introduces a non-perturbative bosonization method to analyze bilayer quantum Hall systems at total filling factor 1, revealing conditions for exciton condensate formation and phase transitions.

Contribution

It develops a systematic bosonization approach and derives an effective model to study exciton condensation and phase transitions in bilayer quantum Hall systems.

Findings

Exciton condensate exists only at very small interlayer distances.

A phase transition may occur before the incompressible to compressible transition.

Finite interlayer tunneling effects are quantitatively analyzed.

Abstract

We develop a non-perturbative bosonization approach for bilayer quantum Hall systems at \nu_T = 1, which allows us to systematically study the existence of an exciton condensate in these systems. An effective boson model is derived and the excitation spectrum is calculated both in the Bogoliubov and in the Popov approximations. In the latter case, we show that the ground state of the system is an exciton condensate only when the distance between the layers is very small compared to the magnetic length, indicating that the system possibly undergoes another phase transition before the incompressible-compressible one. The effect of a finite electron interlayer tunnelling is included and a quantitative phase diagram is proposed.