NMR study of borocarbide superconductor Y(Ni1-xMx)2B2C (M = Co, Cu, Pd, Pt)

11B NMR studies in Y(Ni1-xMx)2B2C with M = Co, Cu, Pd and Pt were performed. The measured nuclear spin-lattice relaxation rates, T-11.s, in the normal state suggest the density of states at EF for B site decrease by the substitution of these impurities for Ni site, which may be accompanied by the decrease of Tc. In the superconducting state, on the other hand, T-11 of 59Co decreases with decreasing temperature exponentially as exp(-Δ/kBTc) with no appreciable enhancement just below Tc. The value of 2Δ/kBTc was estimated to be about 3 down to 0.5 Tc, which is close to the BCS-value of 3.5. (orig.)