# Transport evidence for a sliding two-dimensional quantum electron solid

## TL;DR

This study provides transport evidence supporting the existence of a quantum Wigner crystal in a 2D electron system, showing two-threshold behavior and noise characteristics similar to vortex depinning in superconductors.

## Contribution

It offers the first experimental transport evidence consistent with a quantum electron solid in a 2D system, using a novel model adapted from vortex physics.

## Key findings

- Two-threshold voltage-current characteristics observed
- Dramatic noise increase between thresholds
- Model adapted from vortex depinning explains data

## Abstract

Ignited by the discovery of the metal-insulator transition, the behaviour of low-disorder two-dimensional (2D) electron systems is currently the focus of a great deal of attention. In the strongly-interacting limit, electrons are expected to crystallize into a quantum Wigner crystal, but no definitive evidence for this effect has been obtained despite much experimental effort over the years. Here, studying the insulating state of a 2D electron system in silicon, we have found two-threshold voltage-current characteristics with a dramatic increase in noise between the two threshold voltages. This behaviour cannot be described within existing traditional models. On the other hand, it is strikingly similar to that observed for the collective depinning of the vortex lattice in Type-II superconductors. Adapting the model used for vortexes to the case of an electron solid yields good agreement with our experimental results, favouring the quantum electron solid as the origin of the low-density state.