Field Re-entrant Superconductivity Induced by the Enhancement of Effective Mass in URhGe

Abstract

High quality single crystals of a ferromagnetic superconductor URhGe were successfully grown. The electrical resistivity was measured for the field along b -axis in the orthorhombic crystal structure in order to study precisely its field re-entrant superconductivity which occurs in the vicinity of the field H R , where the easy magnetization switches from c - to b -axis. The field re-entrant superconductivity of URhGe is analyzed with special focus on its dependence with the value of residual resistivity ρ 0 and the coefficient A of T 2 term of the resistivity. The experimental results are well explained by a crude model related with the field dependence of the effective mass m * , where the corresponding critical temperature T sc ( m * ) and the upper critical field H c2 are strongly enhanced. Discussion is made on the interplay between magnetic and superconducting phase diagram as well as the link between T sc and A in other heavy fermion superconductors.