Stress- and temperature-dependent hysteresis in shear modulus of solid helium

TL;DR

This paper investigates how the shear modulus of solid helium varies with temperature and drive strain, revealing hysteresis linked to dislocation dynamics and constructing a phase diagram of its behavior.

Contribution

It provides a systematic study of drive strain and temperature effects on solid helium's shear modulus, highlighting hysteresis and its relation to dislocation theory.

Findings

Shear modulus increases below 200 mK with hysteresis.

Hysteretic behavior depends on drive and cooling history.

A phase diagram of shear modulus behavior is constructed.

Abstract

The shear modulus of solid 4He below 200 mK exhibits an unusual increase, the characteristics of which show remarkable similarities to those of the period reduction in torsional oscillator experiments. We systematically studied the drive strain and temperature dependence of the shear modulus at low temperatures. The hysteretic behavior depends strongly on the drive and cooling history, which can be associated with the thermally assisted Granato-Lucke dislocation theory. The phase diagram of the shear modulus is constructed on the basis of the emerging hysteretic behavior.