Correlated States of Electrons in Wide Quantum Wells at Low Fillings: The Role of Charge Distribution Symmetry

TL;DR

This study investigates how the symmetry of charge distribution in wide quantum wells influences correlated electron states at low Landau level fillings, revealing symmetry-dependent emergence and suppression of fractional quantum Hall states and insulating phases.

Contribution

It demonstrates the critical role of charge distribution symmetry in modulating correlated electron states in wide quantum wells at low fillings.

Findings

Fractional quantum Hall state at ν=1/4 appears only in symmetric charge distributions.

Asymmetry suppresses the ν=1/4 fractional quantum Hall state.

Asymmetry enhances insulating phases near ν=1/5 at lower densities.

Abstract

Magneto-transport measurements on electrons confined to a 57 nm-wide, GaAs quantum well reveal that the correlated electron states at low Landau level fillings ($\nu$) display a remarkable dependence on the symmetry of the electron charge distribution. At a density of $1.93 \times 10^{11}$ cm$^{-2}$, a developing fractional quantum Hall state is observed at the even-denominator filling $\nu = 1/4$ when the distribution is symmetric, but it quickly vanishes when the distribution is made asymmetric. At lower densities, as we make the charge distribution asymmetric, we observe a rapid strengthening of the insulating phases that surround the $\nu = 1/5$ fractional quantum Hall state.