Spin diffusion in liquid 3He confined in nafen

TL;DR

This paper investigates how liquid helium-3's spin diffusion behaves when confined in nafen, a new aerogel with aligned strands, revealing anisotropic diffusion and comparing experimental results with theoretical models.

Contribution

It provides the first measurements of spin diffusion anisotropy in liquid 3He within nafen and develops a theory to explain the observed effects.

Findings

Spin diffusion is anisotropic in nafen due to strand alignment.

Experimental data agrees with the developed theoretical model.

Different porosities affect the degree of diffusion anisotropy.

Abstract

We report results of spin diffusion measurements in normal phase of liquid 3He confined in nafen. Nafen is a new type of aerogel and it consists of Al2O3 strands which are nearly parallel to one another at macroscopic distances. We examine two samples of nafen with different porosities using spin echo techniques. Spin diffusion of 3He along and across the strands was measured. The aerogel alignment is clearly evident from observed spin diffusion anisotropy. A theory describing this effect is developed and compared with the experiment.