Longitudinal and Transverse NMR in Superfluid 3He in Anisotropic Aerogel

TL;DR

This paper investigates how anisotropic aerogel affects the NMR properties of superfluid helium-3, demonstrating that anisotropy influences the order parameter orientation and that isotropic NMR responses can be achieved through squeezing.

Contribution

It shows that the NMR properties of superfluid helium-3 in anisotropic aerogel can be described using bulk superfluid models with fixed orbital vectors, and introduces a method to achieve isotropic NMR responses.

Findings

NMR properties are linked to bulk superfluid order parameters.

Anisotropy fixes the orbital order parameter vector.

Proper squeezing can produce isotropic NMR properties.

Abstract

It was found that NMR properties of both superfluid phases of $^3$He in anisotropic aerogel can be described in terms of the bulk superfluid order parameters with the orbital order parameter vector fixed by anisotropy of the aerogel sample. It was also shown that by a proper squeezing it is possible to get the aerogel sample with isotropic NMR properties.