Supersonic dislocations observed in a plasma crystal

TL;DR

This paper reports the observation of supersonic dislocation motion in a plasma crystal, revealing detailed dislocation dynamics and Mach cone formation at an atomistic level.

Contribution

It provides experimental evidence of dislocations moving faster than shear wave speed in a plasma crystal, a phenomenon not previously observed directly.

Findings

Dislocations are created where shear stress exceeds a threshold.

Dislocations move faster than shear wave speed, generating Mach cones.

The process involves an initial stacking fault stage.

Abstract

Experimental results on the dislocation dynamics in a two-dimensional plasma crystal are presented. Edge dislocations were created in pairs in lattice locations where the internal shear stress exceeded a threshold and then moved apart in the glide plane at a speed higher than the sound speed of shear waves, $C_T$. The experimental system, a plasma crystal, allowed observation of this process at an atomistic (kinetic) level. The early stage of this process is identified as a stacking fault. At a later stage, supersonically moving dislocations generated shear-wave Mach cones.