Wigner crystal in a two-dimensional electron system in the vicinity of filling factor 1/5: Acoustic studies

TL;DR

This study uses acoustic wave measurements to confirm the formation of pinned Wigner crystals in a two-dimensional electron system near filling factor 1/5, revealing insights into the insulating states in GaAs quantum wells.

Contribution

It provides direct acoustic evidence for Wigner crystal formation near filling factor 1/5 in high-quality GaAs quantum wells, advancing understanding of electron solid phases.

Findings

Insulating states near ν=1/5 are pinned Wigner crystals.

Surface acoustic wave measurements confirm the crystal phase.

The complex AC conductance indicates electron localization.

Abstract

By simultaneous measurements of the attenuation and velocity of surface acoustic waves propagating in proximity to a high-quality GaAs quantum well we study the complex AC conductance of the two-dimensional electron system. Focusing on the vicinity of the filling factor $\nu=1/5$ we confirm that the insulating states formed closely to this value of $\nu$ are pinned Wigner crystals.