Magnetic Field Effect On S-Wave Superconductor Laru4p12 Studied By P-31-Nmr

We have performed P-31-NMR measurements on the s-wave superconductor LaRu4P12 to investigate the magnetic field effect of the nuclear spin-lattice relaxation rate 1/T-1 on a conventional full-gap superconductor. With increasing magnetic field, the Hebel-Slichter peak immediately below T-c in 1/T-1 was suppressed, and the magnetic field dependence of 1/T-1 at 0.8 K, well below T-c, was proportional to H-2. These behaviors can be fully understood by the orbital pair-breaking effect in a single-band s-wave superconductor.