Superclimb of Dislocations and the Anomalous Isochoric Compressibility of Solid He4

TL;DR

This paper investigates the anomalously large isochoric compressibility observed in solid He4, proposing superclimb of dislocations as the underlying mechanism supported by ab initio simulations.

Contribution

It introduces the superclimb of dislocations as a novel explanation for the compressibility anomaly in solid He4, supported by computational simulations.

Findings

Superclimb of dislocations can cause large density responses.

Ab initio simulations confirm dislocation climb at low temperature.

Effect likely suppressed at very low temperatures due to dislocation crossover.

Abstract

In the experiment on superfluid transport in solid He4 [PRL {\bf 100}, 235301 (2008)], Ray and Hallock observed an {\it anomalously large isochoric compressibility}: the supersolid samples demonstrated a significant and apparently spatially uniform response of density and pressure to chemical potential, applied locally through Vycor "electrodes". We propose that the effect is due to {\it superclimb} : edge dislocations can climb because of mass transport along superfluid cores. We corroborate the scenario by {\it ab initio} simulations of an edge dislocation in solid He4 at $T=0.5K$. We argue that at low temperature the effect must be suppressed due to a crossover to the smooth dislocation.