New Chiral Phases of Superfluid 3He Stabilized by Anisotropic Silica Aerogel

TL;DR

This paper reports the discovery of new chiral superfluid phases of helium-3 stabilized by anisotropic silica aerogel, revealing unique orientation properties and a transition to a disordered state at low temperatures.

Contribution

It demonstrates that anisotropic disorder from silica aerogel can stabilize chiral superfluid phases of helium-3, a novel finding in superfluid physics.

Findings

Anisotropic silica aerogel stabilizes chiral superfluid 3He.

Magnetic field orients the chiral axis uniquely.

Low temperature transition to a disordered domain structure.

Abstract

A rich variety of Fermi systems condense by forming bound pairs, including high temperature [1] and heavy fermion [2] superconductors, Sr2RuO4 [3], cold atomic gases [4], and superfluid 3He [5]. Some of these form exotic quantum states having non-zero orbital angular momentum. We have discovered, in the case of 3He, that anisotropic disorder, engineered from highly porous silica aerogel, stabilizes a chiral superfluid state that otherwise would not exist. Additionally, we find that the chiral axis of this state can be uniquely oriented with the application of a magnetic field perpendicular to the aerogel anisotropy axis. At suffciently low temperature we observe a sharp transition from a uniformly oriented chiral state to a disordered structure consistent with locally ordered domains, contrary to expectations for a superfluid glass phase [6].