Ginzburg-Landau Theory for Impure Superfluid 3He

TL;DR

This paper develops a Ginzburg-Landau theoretical framework for superfluid 3He in aerogel, analyzing impurity effects on its properties and comparing predictions with experimental data.

Contribution

It introduces a Ginzburg-Landau theory for impure superfluid 3He using the homogeneous scattering model, extending understanding of impurity effects.

Findings

Derived expressions for measurable quantities in impure superfluid 3He.

Analyzed the impact of random anisotropy on NMR properties.

Compared theoretical predictions with experimental results.

Abstract

Liquid 3He at low temperatures is an ideal substance to study because of its natural purity. The superfluid state, which appears at temperatures below 3 mK, has many unusual and exciting properties. These have extensively been studied experimentally, and the results are in many cases well understood theoretically using quasiclassical approximation. In this work we study the case that liquid 3He is inside of aerogel. Aerogel is a very porous substance, where 98% of the volume can be empty. The purpose is to understand how the properties of the superfluid are modified when the quasiparticles are scattered from an impurity, such as aerogel. We study extensively the "homogeneous scattering model". From it we derive the Ginzburg-Landau theory of impure superfluid 3He. We give expressions for measurable quantities and compare them with experiments. We consider random anisotropy and its effect on the NMR properties. More sophisticated scattering models are briefly discussed.