Pressure Evolution of the Ferromagnetic and Field Re-entrant Superconductivity in URhGe

Fine pressure (P) and magnetic field (H) tuning on the ferromagnetic superconductor URhGe are reported in order to clarify the interplay between the mass enhancement, low field superconductivity (SC) and field reentrant superconductivity (RSC) by electrical resistivity measurements. With increasing P, the transition temperature and the upper critical field of the low field SC decrease slightly, while the RSC dome drastically shifts to higher fields and shrinks. The spin reorientation field H-R also increases. At a pressure P similar to 1.8 GPa, the RSC has collapsed while the low field SC persists and may disappear only above 4 GPa. Via careful (P, H) studies of the inelastic T-2 resistivity term, it is demonstrated that this drastic change is directly related with the P dependence of the effective mass which determines the critical field of the low field SC and RSC on the basis of triplet SC without Pauli limiting field.