Vortex phase diagram of rotating superfluid He 3 - B

Artikel i vetenskaplig tidskrift, 2020

We present a theoretical calculation of the pressure-temperature-field phase diagram for the vortex phases of rotating superfluid He3-B. Based on a strong-coupling Ginzburg-Landau functional that accounts for the relative stability of the bulk A and B phases of He3 at all pressures, we report calculations for the internal structure and free energies of distinct broken-symmetry vortices in rotating superfluid He3-B. Theoretical results for the equilibrium vortex phase diagram in zero field and an external field of H=284G parallel to the rotation axis, H∥ω, are reported, as well as the supercooling transition line, TV∗(p,H). In zero field the vortex phases of He3-B are separated by a first-order phase transition line TV(p) that terminates on the bulk critical line Tc(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, TV∗(p,H), below which it is globally unstable to an array of D-core vortices. For H≳60G external magnetic fields aligned along the axis of rotation increase the region of stability of the A-core phase of rotating He3-B, opening a window of stability down to low pressures. These results are compared with the experimentally reported phase transitions in rotating He3-B.