Observation of fractional quantum Hall effect at even-denominator 1/2 and 1/4 fillings in asymmetric wide quantum wells

TL;DR

This paper reports the experimental observation of fractional quantum Hall states at fillings 1/2 and 1/4 in asymmetric wide GaAs quantum wells, suggesting these are one-component states possibly described by the Moore-Read Pfaffian wavefunction.

Contribution

First observation of fractional quantum Hall states at 1/2 and 1/4 in asymmetric wide quantum wells with implications for non-Abelian states.

Findings

Quantum Hall states observed at ν=1/2 and 1/4

States disappear when charge distribution is symmetric

States likely described by Moore-Read Pfaffian wavefunction

Abstract

We report the observation of developing fractional quantum Hall states at Landau level filling factors $\nu = 1/2$ and 1/4 in electron systems confined to wide GaAs quantum wells with significantly $asymmetric$ charge distributions. The very large electric subband separation and the highly asymmetric charge distribution at which we observe these quantum Hall states, together with the fact that they disappear when the charge distribution is made symmetric, suggest that these are one-component states, possibly described by the Moore-Read Pfaffian wavefunction.