Evidence of the Bound States of the Vortex State in ans-Wave Superconductor Proved by NMR Measurements

Abstract

In the s -wave superconductor LaRu 4 P 12 ( T c =7.2 K), a clear Redfield pattern was observed below T c , which arises from a triangular lattice. We observed distinct frequency dependence of the spin–lattice relaxation rate 1/ T 1 in the vortex state in contrast to the normal state. In addition, from the T -dependence of 1/ T 1 T measured at different frequencies, 1/ T 1 T at the vortex core is considered to be greater than that in the normal state, indicating that the LDOS in the vortex core region is higher than that in the normal state. This enhancement of the LDOS in the core region can be understood in terms of the bound states inside a vortex core.