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arXiv · 2105.01257

Half-Quantum Vortices in Nematic and Chiral Phases of $^3$He

Robert C. Regan·Joshua J. Wiman·J. A. Sauls
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Abstract

We report theoretical results for the stability of half-quantum vortices (HQVs) in the superfluid phases of $^3$He confined in highly anisotropic Nafen aerogel. Superfluidity of $^3$He confined in Nafen is the realization of a "nematic superfluid" with Cooper pairs condensed into a single p-wave orbital aligned along the anisotropy axis of the Nafen aerogel. In addition to the nematic phase, we predict a second "chiral" phase that onsets at a lower transition temperature. This chiral phase spontaneously breaks time-reversal symmetry and is a topological superfluid. Both superfluid phases are equal-spin pairing condensates that host arrays of HQVs as equilibrium states of rotating superfluid $^3$He. We present results for the structure of HQVs, including magnetic and topological signatures of HQVs in both the nematic and chiral phases of $^3$He-Nafen.

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Robert C. Regan, Joshua J. Wiman, J. A. Sauls. 2021-05-04. Half-Quantum Vortices in Nematic and Chiral Phases of $^3$He. https://doi.org/10.1103/physrevb.104.024513

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