Two-fluid theory of composite bosons and fermions and the quantum Hall proximity effect

TL;DR

This paper introduces a two-fluid model for fractional quantum Hall systems combining composite bosons and fermions, and explores the quantum Hall proximity effect at interfaces with Fermi liquids, revealing new gapped modes.

Contribution

It presents a novel two-fluid theoretical framework for fractional quantum Hall systems and models the proximity effect at quantum Hall-metal interfaces.

Findings

Quantum Hall condensate penetrates into metallic regions.

Identification of new gapped quasielectron and neutral modes.

Modeling of the interface behavior between quantum Hall liquids and Fermi liquids.

Abstract

We propose a two-fluid description of fractional quantum Hall systems, in which one component is a condensate of composite bosons and the other a Fermi liquid formed by composite fermions (or simply electrons). We employ the theory to model the interface between a fractional quantum Hall liquid and a (composite) Fermi liquid metal, where we find a penetration of quantum Hall condensate into the metallic region reminiscent of the proximity effect in superconductor-metal interfaces. We also find a novel and physically reasonable set of gapped quasielectron and neutral modes in fractional quantum Hall liquids.