Quantum plasticity and dislocation-induced supersolidity

TL;DR

This paper proposes that below a certain temperature, dislocation dynamics in solid He4 lead to supersolidity and stiffening, driven by vacancy liberation and permutation cycles, revealing a novel quantum plasticity mechanism.

Contribution

It introduces a new theoretical framework linking dislocation behavior and vacancy cycles to supersolidity in solid helium-4.

Findings

Dislocation networks become more mobile below T_k.

Superfluid fraction appears below T_c.

Solid stiffens at low temperatures.

Abstract

We suggest that below a certain temperature T_k, the free energy for the creation of kinks-antikinks pairs in the dislocation network of solid He4 becomes negative. The underlying physical mechanism is the related liberation of vacancies which initiate Feynman's permutation cycles in the bulk. Consequently, dislocations should wander and sweep an increasingly larger volume at low temperatures. This phenomenon should lead both to a stiffening of the solid below T_k and to the appearance of a non zero superfluid fraction at a second temperature T_c < T_k.