NMR study of borocarbide superconductor RENi2B2C

Measurements of the spin-lattice relaxation rate. (T-1)(-1), of B-11 in REN i2B2C with R-E = Y. Lu and Th and in Y(Ni0.8Co0.2)(2) B2C have been carried out in a wide temperature (T) range. In the normal st;lte, the values of(T -1 T)(-1) in RE = Y and Lu increase with decreasing T presumably due to the antiferromagnetic (AF) spin fluctuations. (T-1 T)(-1) in R-E = Th obeys th e Korringa relation below 150 K, while (T-1 T)(-1) is weakly T dependent ab ove 150 K. (T-1)(-1) of B-11-and C-13-NMR in the superconducting state decr ease rapidly with decreasing T with no appreciable enhancement just below T -c. successively vary in proportion to temperature at further low T. Simila r behaviors of (T-1)(-1) have already been observed in Cu-NQR and NMR of Zn -doped high T-c cuprates where d-wave superconductivity is realized. (C) 20 00 Elsevier Science B.V. All rights reserved.