Intrinsic gap and exciton condensation in the nu_T=1 bilayer system

TL;DR

This paper explores the quasiparticle excitations in a bilayer quantum Hall system at total filling factor one, revealing their pseudospin origin and the role of exciton formation in phase transitions.

Contribution

It introduces a model based on exciton formation that explains the quasiparticle excitation gap and links the excitonic quantum Hall state with the composite fermion liquid.

Findings

Quasiparticle excitations are of pseudospin origin.

Exciton formation explains the excitation gap behavior.

Provides insights into phase transition mechanisms.

Abstract

We investigate the quasiparticle excitation of the bilayer quantum Hall (QH) system at total filling factor $\nu_{\mathrm{T}} = 1$ in the limit of negligible interlayer tunneling under tilted magnetic field. We show that the intrinsic quasiparticle excitation is of purely pseudospin origin and solely governed by the inter- and intra-layer electron interactions. A model based on exciton formation successfully explains the quantitative behavior of the quasiparticle excitation gap, demonstrating the existence of a link between the excitonic QH state and the composite fermion liquid. Our results provide a new insight into the nature of the phase transition between the two states.