Chirality of superfluid 3He-A

TL;DR

This study investigates the chiral textures of superfluid 3He-A using torsional oscillators, revealing how rotation influences texture orientation, vortex formation, and chirality bias in the superfluid state.

Contribution

It provides experimental evidence of chiral orbital textures and their dependence on rotation and vortex energy differences in superfluid 3He-A.

Findings

Oriented monodomain texture with l antiparallel to rotation axis after stopping rotation.

Bias towards a specific chirality due to vortex energy inequivalence.

Critical velocity for vortex nucleation depends on rotation direction.

Abstract

We have used torsional oscillators, containing disk-shaped slabs of superfluid 3He-A, to probe the chiral orbital textures created by cooling into the superfluid state while continuously rotating. Comparing the observed flow-driven textural transitions with numerical simulations of possible textures shows that an oriented monodomain texture with l antiparallel to the angular velocity Omega_0 is left behind after stopping rotation. The bias towards a particular chirality, while in the vortex state, is due to the inequivalence of energies of vortices of opposite circulation. When spun-up from rest, the critical velocity for vortex nucleation depends on the sense of rotation, Omega, relative to that of l. A different type of vorticity, apparently linked to the slab's rim by a domain wall, appears when Omega is parallel to l.