CMT160

The Vortex Phase Diagram for Rotating Superfluid ³He-B

• Author(s): Robert C. Regan, Joshua J. Wiman and J. A. Sauls
• Address: Department of Physics, Northwestern University, Evanston, IL 60208
• Date: August 15, 2019
• Journal: Physical Review B 101, 024517 (2020) [DOI] [PDF]
• Abstract: We present the first theoretical calculation of the pressure-temperature-field phase diagram for the vortex phases of rotating superfluid ³He-B. Based on a strong-coupling extension of the Ginzburg-Landau theory that accounts for the relative stability of the bulk A and B phases of ³He at all pressures, we report calculations for the internal structure and free energies of distinct broken-symmetry vortices in rotating superfluid ³He-B. Theoretical results for the equilibrium vortex phase diagram in zero field and an external field of H=284 G parallel to the rotation axis, H||Ω, are reported, as well as the supercooling transition line, T^*_V(p,H). In zero field the vortex phases of ³He-B are separated by a first-order phase transition line T_V(p) that terminates on the bulk critical line T_c(p) at a triple point. The low-pressure, low-temperature phase is characterized by an array of singly-quantized vortices that spontaneously breaks axial rotation symmetry, exhibits anisotropic vortex currents and an axial current anomaly (D-core phase). The high-pressure, high-temperature phase is characterized by vortices with both bulk A phase and β phase in their cores (A-core phase). We show that this phase is metastable and supercools down to a minimum temperature, T^*_V(p,H), below which it is globally unstable to an array of D-core vortices. For H >~60 G external magnetic fields aligned along the axis of rotation increase the region of stability of the A-core phase of rotating ³He-B, opening a window of stability down to low pressures. These results are compared with the experimentally reported phase transitions in rotating ³He-B.

• Comment: 14 pages, 11 figures

• Eprint: [PDF] [arXiv]

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