Anisotropy-induced Vortex Core Transitions in Superfluid 3He in Aerogel

Core structures of a single vortex in A-like and B-like phases of superfluid 3He in uniaxially compressed and stretched aerogels are studied by numerically solving Ginzburg-Landau equations derived microscopically. It is found that, although the A-like phase with axial pairing is extended by any uniaxial deformation, the vortex core states in the two phases depend highly on the type of deformation in aerogel: In a compressed aerogel, the first order vortex core transition (VCT) previously seen in the bulk B phase appears at any pressure in B-like phase, while no strange vortex core is expected in A-like phase. By contrast, in a stretched aerogel, the VCT in B-like phase is lost, while another VCT is expected to occur between a nonunitary core and the polar one in A-like phase. An experimental search for these results is hoped to understand correlation between superfluid $^3$He and aerogel structures.