Paired States in the Even Integer Quantum Hall Effect

TL;DR

This paper proposes a new paired quantum Hall state at low electron density involving spin pairing and bosonic condensation, expanding the understanding of the integer quantum Hall effect with spin.

Contribution

It introduces a novel paired quantum Hall state at =2, stabilized by a BCS instability, and develops a new phase diagram for the spin-involved integer quantum Hall effect.

Findings

Identification of a paired state at =2

Derivation of a new phase diagram including spin effects

Discussion of experimental implications

Abstract

We argue that a new type of quantum Hall state requiring non-perturbative Landau level mixing arises at low electron density. In these states, up and down spin electrons pair to form spinless bosons that condense into a bosonic quantum Hall state. We describe a wavefunction for a paired quantum Hall state at $\nu=2$ and argue that it is stabilized by a BCS instability arising in flux attachment calculations. Based on this state, we derive a new global phase diagram for the integral quantum Hall effect with spin. Additional experimental implications are discussed.