NMR-STUDY OF THE SUPERCONDUCTOR RNI(2)B(2)C (R=Y,LU)

Measurements of the B-11 NMR spectrum and spin-lattice relaxation rate , 1/T-1 in the normal and the superconducting stares of a quaternary b oro-carbide superconductor RNi(2)B(2)C (R = Y, Lu) are reported. In th e superconducting stale, two kinds of B-11 NMR spectra have been obser ved; one B-11 signal comes from the superconducting region in the samp le and shifts to higher magnetic field due to the demagnetizing field, the other from the normal-metal region with no appreciable shifts. Wi th decreasing temperature, 1/T, in the superconducting state decreases rapidly with no appreciable enhancement just below T-c. In the normal slate, 1/T1T increases with decreasing temperature presumably due to antiferromagnetic Ni spin fluctuations. Similar behaviors on B NMR in RNi(2)B(2)C (R = Y, Lu) were observed in the normal and the supercondu cting states.