Helical spin texture in a thin film of superfluid ${}^3$He

TL;DR

This paper predicts a stable helical spin texture in a thin superfluid ${}^3$He film under superflow and magnetic field, with tunable length scale, based on symmetry considerations.

Contribution

It introduces a novel helical spin texture in superfluid ${}^3$He films induced by superflow and magnetic field, grounded in symmetry principles.

Findings

Helical spin texture forms under specific conditions.

The helical order's length scale is tunable.

Prediction is robust and experimentally accessible.

Abstract

We consider a thin film of superfluid ${}^3$He under conditions that stabilize the A-phase. We show that in the presence of a uniform superflow and an external magnetic field perpendicular to the film, the spin degrees of freedom develop a nonuniform, helical texture. Our prediction is robust and relies solely on Galilei invariance and other symmetries of ${}^3$He, which induce a coupling of the orbital and spin degrees of freedom. The length scale of the helical order can be tuned by varying the velocity of the superflow and the magnetic field, and may be in reach of near-future experiments.