Evolution of $nu=1$ Bilayer Quantum Hall Ferromagnet

TL;DR

This paper investigates the ground state properties of a bilayer quantum Hall system at total filling factor one, revealing phase coherence phenomena, questioning the relevance of the (1,1,1) state near phase transitions, and proposing an effective model.

Contribution

It introduces an effective model for the ground state and discusses its relation to modified composite fermion theory, challenging existing assumptions about the (1,1,1) state.

Findings

Spontaneous interlayer phase coherence at small layer separations

The (1,1,1) state is not relevant near the transition point

Correlation hole is deflated in the transition regime

Abstract

The natures of the ground state in a $\nu_{\rm T}=1$ bilayer quantum Hall system at a variety of layer spacing are investigated. At small layer separations the system exhibits spontaneous interlayer phase coherence. It is claimed that the Halperin's (1,1,1) state is not relevant in the incompressible regime near the incompressible to compressible transition point in which the Josephson-like effect was observed. The two-particle correlation function shows the deflated correlation hole at this regime. An effective model that can give a good approximation to the ground state is proposed. A connection to the modified composite fermion theory is discussed.