Evidence for A Two-dimensional Quantum Wigner Solid in Zero Magnetic Field

TL;DR

This paper presents the first experimental evidence of a two-dimensional quantum Wigner solid in zero magnetic field, characterized by nonlinear response and voltage oscillations in high-purity GaAs 2D hole systems.

Contribution

It provides the first experimental observation of quantum Wigner crystallization in 2D systems without magnetic fields, revealing unique pinning and depinning mechanisms.

Findings

Observation of voltage oscillations with negative differential resistance

Evidence of a moving crystal coexisting with striped edge states

Threshold behavior below classical levels indicating quantum effects

Abstract

We report the first experimental observation of a characteristic nonlinear threshold behavior from dc dynamical response as an evidence for a Wigner crystallization in high-purity GaAs 2D hole systems in zero magnetic field. The system under increasing current drive exhibits voltage oscillations with negative differential resistance. They confirm the coexistence of a moving crystal along with striped edge states as observed for electrons on helium surfaces. However, the threshold is well below the typical classical levels due to a different pinning and depinning mechanism that is possibly related to a quantum process.