Fulde-Ferrell state in ferromagnetic chiral superconductor with magnetic domain wall: application to UCoGe.
We study a ferromagnetic chiral superconductor in the presence of magnetic domains with a focus on the heavy fermion system UCoGe. Within mean field approximations, it is shown that chiral superconducting domains are naturally induced by the ferromagnetic domains. The domain wall current flows in the opposite direction to the naively expected one as in $^3$He-A phase due to contributions from "unpaired electrons". Consequently, the domain wall current flows in the same direction with that of surface currents when the magnetic domain wall lies parallel to the sample surface, and therefore they contribute to the net current along the whole sample. We find that, due to the non-cancellation between the domain wall current and surface current, a Fulde-Ferrell-like superconducting state can be stabilized in thin film geometry for all the temperatures below the superconducting transition temperature.
Publisher URL: http://arxiv.org/abs/1711.00635