Stability of the A-like Phase of Superfluid 3He in Aerogel with Globally Anisotropic Scattering

TL;DR

This study investigates whether uniaxial compression of silica aerogel stabilizes the A-phase of superfluid helium-3, finding that such anisotropic scattering does not promote the axial phase in highly porous aerogel.

Contribution

The paper provides experimental phase diagram data showing that uniaxial compression does not stabilize the A-phase of superfluid 3He in aerogel, challenging previous theoretical suggestions.

Findings

Uniaxial compression of 17% does not stabilize the A-phase.

Phase diagram measurements were conducted using transverse acoustic impedance.

Anisotropic scattering alone may not be sufficient to stabilize the A-phase.

Abstract

It has been suggested that anisotropic quasiparticle scattering will stabilize anisotropic phases of superfluid $^3$He contained within highly porous silica aerogel. For example, global anisotropy introduced via uniaxial compression of aerogel might stabilize the axial state, which is called the A-phase in bulk superfluid 3He. Here we present measurements of the phase diagram of superfluid 3He in a 98% porous silica aerogel using transverse acoustic impedance methods. We show that uniaxial compression of the aerogel by 17% does not stabilize an axial phase.