Effect of a quenched disorder on the order parameter of superfluid 3He

TL;DR

This paper investigates how quenched disorder from aerogel affects the order parameter of superfluid 3He, highlighting the disruption of long-range order and identifying quasi-isotropic order parameters that are less sensitive to disorder.

Contribution

It analyzes the impact of quenched disorder on superfluid 3He’s order parameter and discusses potential candidates for the A-like phase’s order parameter.

Findings

Quenched disorder disrupts long-range orientational order.

Certain quasi-isotropic order parameters are insensitive to aerogel.

The ABM order parameter is sensitive to disorder.

Abstract

As a consequence of a continuous degeneracy of the order parameter of the superfluid 3He the quenched disorder in a form of aerogel gives rise both to a disruption of the orientational long-range order of the condensate and to a significant change of the order parameter itself. There exist a class of quasi-isotropic order parameters which are not sensitive to the disorienting effect of aerogel. While the BW order parameter belongs to this class the ABM does not. Possible candidate for the order parameter of the observed A-like phase is discussed.