Direct experimental measurement of the speed-stress relation for dislocations in a plasma crystal

TL;DR

This study experimentally measured the speed-stress relation for dislocations in a plasma crystal, revealing subsonic to supersonic transitions and real-time atomistic-level observations of dislocation dynamics.

Contribution

First direct measurement of dislocation speed-stress relation in a plasma crystal, providing real-time, atomistic-level insights into dislocation motion and speed transitions.

Findings

Dislocations move subsonically at low stress.

Dislocations accelerate to 1.9 times shear wave speed at higher stress.

Dislocations can move faster than pressure waves immediately after nucleation.

Abstract

The speed-stress relation for gliding edge dislocations was experimentally measured for the first time. The experimental system used, a two-dimensional plasma crystal, allowed observation of individual dislocations at the "atomistic" level and in real time. At low applied stress dislocations moved subsonically, at higher stress their speed abruptly increased to 1.9 times the speed of shear waves, then slowly grew with stress. There is evidence that immediately after nucleation dislocations can move faster than pressure waves.