Orientational effect of uniaxially deformed aerogel on the order parameter of superfluid $^3He$

TL;DR

This paper investigates how uniaxial deformation of aerogel influences the orientation of the superfluid $^3$He$'$s order parameter, revealing that even small strains can significantly alter its orientation, with correlations in aerogel particles playing a crucial role.

Contribution

It introduces a model accounting for particle correlations in aerogel to analyze their impact on superfluid $^3$He$'$s order parameter orientation under uniaxial deformation.

Findings

Uniaxial stretching of aerogel can reorient the superfluid $^3$He$'$s order parameter.

Correlations in aerogel particles significantly affect the order parameter orientation.

The effect on orientation is stronger than on the transition temperature.

Abstract

Effect of uniaxially-deformed aerogel on orientation of the order parameter of superfluid $^3He$ is considered. Approach used takes into account correlations in positions of particles forming aerogel. Calculations show that for the case of the B-like phase in the uniaxially-stretched aerogel deformation on the order of $10^{-2}\div10^{-4}$ is already strong enough to achieve orientation of the order parameter which is different from that required by magnetic field in bulk liquid. For the A-like phase in uniaxially-squeezed aerogel the order of magnitude of the orientational effect is estimated. It is shown that the correlations in positions of particles forming aerogel has stronger effect on the orientation of the order parameter than on the transition temperature.