Order parameter of A-like phase of $^3$He in aerogel

TL;DR

This paper proposes a phenomenological criterion for selecting the order parameter of superfluid $^3$He in aerogel near the transition temperature, suggesting the A-like phase corresponds to an axiplanar phase under specific conditions.

Contribution

It introduces a new criterion for choosing the order parameter of superfluid $^3$He in aerogel and identifies the axiplanar phase as the likely form of the A-like phase near $T_c$.

Findings

The criterion favors the axiplanar phase for the A-like phase.

The axiplanar phase is proposed as the limiting form of the order parameter near $T_c$.

The study provides a theoretical basis for understanding the order parameter in $^3$He in aerogel.

Abstract

Phenomenological criterion of a choice of the order parameter for superfluid phases of $^3$He in aerogel in a near vicinity of the transition temperature is formulated. Except for the B-phase this criterion is met by the order parameter of axiplanar phase for a special choice of its parameters. It is proposed as a limiting at $T\to T_c$ form of the order parameter for the observed A-like phase.