No robust phases in aerogel: 3He-A with orientational disorder in the Ginzburg-Landau model

TL;DR

This paper refutes the existence of robust phases in superfluid 3He in aerogel by correcting previous overestimations of fluctuation energy, showing that disorder destroys long-range order but not local structure.

Contribution

It demonstrates that the interaction of Goldstone modes with disorder leads to the Imry-Ma effect, invalidating the robust phases proposed by Fomin.

Findings

Robust phases do not exist in superfluid 3He with orientational disorder.

Disorder destroys long-range orientational order via the Imry-Ma effect.

Local structure of the A-phase remains intact despite disorder.

Abstract

In series of papers Fomin introduced and discussed the so-called robust phases in a system with frozen orientational disorder (with application to superfluid 3He in aerogel). We show that his consideration is based on the erroneous overestimation of the fluctuation energy which comes from the interaction of the Goldstone modes with the frozen disorder. This interaction leads to the Imry-Ma effect, which destroys the orientational order, but is unable to destroy the local structure of the A-phase. There is no ground for the robust phases.