Superfluid 3He in Aerogel

TL;DR

This paper reviews how superfluid 3He, an unconventional p-wave superfluid, behaves when confined in silica aerogel, revealing new phases and phenomena that serve as models for impurity effects in unconventional superconductors.

Contribution

It highlights the stabilization of new superfluid phases and phenomena in superfluid 3He due to anisotropic aerogels and strain, advancing understanding of impurity effects on unconventional superfluids.

Findings

Discovery of new superfluid phases stabilized by anisotropy.

Observation of sharp thermodynamic transitions in aerogel-confined 3He.

Modeling impurity effects on symmetry and topology of unconventional superconductors.

Abstract

Superfluid 3He is an unconventional neutral superfluid in a p-wave state with three different superfluid phases each identified by a unique set of characteristic broken symmetries and non- trivial topology. Despite natural immunity of 3He from defects and impurity of any kind, it has been found that they can be artificially introduced with high porosity silica aerogel. Furthermore, it has been shown that this modified quantum liquid becomes a superfluid with remarkably sharp thermodynamic transitions from the normal state and between its various phases. They include new superfluid phases that are stabilized by anisotropy from uniform strain imposed on the silica aerogel framework and they include new phenomena in a new class of anisotropic aerogels consisting of nematically ordered alumina strands. The study of superfluid 3He in the presence of correlated, quenched disorder from aerogel, serves as a model for understanding the effect of impurities on the symmetry and topology of unconventional superconductors.