Evidence of zero-field Wigner solids in ultra-thin films of cadmium arsenide

TL;DR

This paper provides experimental evidence of a zero-field Wigner solid in ultra-thin cadmium arsenide films, revealing domain pinning, depinning behavior, and topological transition effects, advancing understanding of electron crystallization in topological materials.

Contribution

First experimental observation of a zero-field Wigner solid in ultra-thin topological Cd3As2 films, linking electron crystallization to topological transitions.

Findings

Finite bias depins Wigner domains and causes sharp I-V thresholds.

Hysteresis and voltage fluctuations indicate domain motion and pinning.

Small magnetic field destroys the Wigner solid, highlighting its unconventional origin.

Abstract

The quantum Wigner crystal is a many-body state where Coulombic repulsion quenches the kinetic energy of electrons, causing them to crystallize into a lattice. Experimental realization of a quantum Wigner crystal at zero magnetic field has been a long-sought goal. Here, we report on the experimental evidence of a Wigner solid in ultra-thin films of cadmium arsenide (Cd3As2) at zero magnetic field. We show that a finite bias depins the domains and produces an unusually sharp threshold current-voltage behavior. Hysteresis and voltage fluctuations point to domain motion across the pinning potential and disappear at finite temperature as thermal fluctuations overcome the potential. The application of a small magnetic field destroys the Wigner solid, pointing to an unconventional origin. We use Landau level spectroscopy to show that the formation of the Wigner solid is closely connected to a topological transition as the film thickness is reduced.