Field-induced reentrant superconductivity driven by quantum tricritical fluctuations in URhGe

Abstract We review our 59 Co NMR study in a URhGe single crystal doped with 10% cobalt. The spin-spin relaxation time ( T 2 ) measurements have revealed a divergence of electronic spin fluctuations in the vicinity of a field-induced tricritical point (TCP) locating around 13 T. The fluctuations is developed in the same limited field region around the TCP as that where a reentrant superconductivity (RSC) is observed in URhGe. The finding strongly suggests these quantum fluctuations as the pairing glue responsible for the RSC.