Extruding the vortex lattice: two reacting populations of dislocations

TL;DR

This paper explores vortex matter in a type II superconductor, revealing a novel plastic flow mechanism involving two interacting dislocation populations that facilitate density and shear stress relaxation in a controllable, non-equilibrium system.

Contribution

It introduces a new understanding of plastic deformation in vortex matter through simulations showing two reacting dislocation populations in a driven non-equilibrium state.

Findings

Identification of two distinct dislocation populations facilitating different relaxation processes

Demonstration of a plastic flow mechanism unique to vortex matter

Ability to vary the 2D unit cell area by a factor of 10^4 without changing symmetry

Abstract

A controllable soft solid is realised in vortex matter in a type II superconductor. The two-dimensional unit cell area can be varied by a factor of $10^4$ in the solid phase, without a change of crystal symmetry offering easy exploration of extreme regimes compared to ordinary materials. The capacity to confine two-dimensional vortex matter to mesoscopic regions provides an arena for the largely unexplored metallurgy of plastic deformation at large density gradients. Our simulations reveal a novel plastic flow mechanism in this driven non-equilibrium system, utilising two distinct, but strongly interacting, populations of dislocations. One population facilitates the relaxation of density; a second aids the relaxation of shear stresses concentrated at the boundaries. The disparity of the bulk and shear moduli in vortex matter ensures the dislocation motion follows the overall continuum flow reflecting density variation.