Reentrant superconductivity in URhGe
Abstract
A phenomenological description of the phase diagram of the ferromagnet superconductor URhGe is presented. In the frame of Landau phenomenological theory it was found that the phase transition between anisotropic ferromagnetic and paramagnetic states under a strong enough magnetic field perpendicular to the direction of easy magnetization changes from the second- to the first-order type. It is shown that magnetic susceptibility corresponding to longitudinal magnetic fluctuations strongly increases in the vicinity of the first-order transition stimulating reentrance of the superconducting state. The reentrant superconductivity observed near the first- order transition line at temperatures about twice lower than the tricritical point temperature exists both in ferromagnet and in paramagnet states. The critical temperature of transition to the superconducting state falls down at the intersection with the line of ferromagnet-paramagnet phase transition.