Effect of Dipole Energy on Half-Quantum Vortex in Superfluid Polar Phase

TL;DR

This paper investigates how dipole energy influences the stability of half-quantum vortices in superfluid 3He within the polar phase, revealing the role of magnetic field orientation and dipole interactions through Ginzburg-Landau theory.

Contribution

It introduces a Ginzburg-Landau free energy framework including dipole energy to explain HQV stability in superfluid polar phase within nematic aerogels.

Findings

HQV stability depends on magnetic field direction relative to anisotropy axis

Dipole energy affects vortex energy and stability

Transverse magnetic fields destabilize HQV in field-cooling conditions

Abstract

NMR experiments on superfluid 3He in a nematic aerogel have shown that the stability of the half-quantum vortex (HQV) realized in the polar phase depends on the relative direction between the magnetic field and the anisotropy axis brought by the aerogel. The vortex energy in the polar phase is examined in terms of the Ginzburg-Landau free energy incorporating the dipole energy, and the reason why the HQV in the polar phase in nematic aerogels became unstable in a transverse magnetic field upon a field-cooling is explained.