Topological spin texture and d-vector rotation in spin-triplet superconductors: A case of UTe2

Abstract

A novel spin texture formed by Cooper pair spins is found theoretically with a phase string attached by half-quantized vortices at both ends in a unit cell and characterized by its topologically rich vortex structure in a spin-triplet pairing. It is stable at an intermediate field region sandwiched by two conventional singular vortex phases below and above it. The d-vector direction of this spin texture is tilted from the principal crystal axes, whose spin susceptibility is neither the normal Pauli one \c{hi}N nor zero, describing microscopically the process of the d-vector rotation phenomena observed recently in UTe2. We compare the spin texture and singular vortex state in relation to the quasi-particle structure with Majorana zero modes for STM, the nuclear spin resonance spectral line width for NMR and μSR, and the vortex form factors for SANS to facilitate the identification of the pairing symmetry in UTe2.

9 pages, 5figures