Impurity Effects of Aerogel in Superfluid $^{3}$He

TL;DR

This paper reviews how silica aerogel impurities affect superfluid helium-3, combining experimental data with theoretical models to deepen understanding of impurity scattering in unconventional superfluids.

Contribution

It provides a comprehensive overview of impurity effects in superfluid helium-3, emphasizing the agreement between experiments and models of homogeneous and inhomogeneous scattering.

Findings

Inhomogeneous scattering models explain most experimental results.

Impurity effects are well-understood due to the well-established order parameter structure.

Quantitative interpretation of experiments supports theoretical models.

Abstract

The discovery of superfluid $^{3}$He in high porosity silica aerogels, and subsequent experimental and theoretical work, have led to a better general understanding of quasiparticle scattering from impurities in unconventional pairing systems. It is immensely helpful for understanding impurity effects in the case of superfluid $^{3}$He that the structure of its order parameter is well-established. An overview of impurity effects is presented with emphasis on those experiments which have a quantitative interpretation in terms of theoretical models for homogeneous and inhomogeneous scattering. The latter can account successfully for most experimental results.