Nuclear Spin-Lattice Relaxation of 139La in Superconducting (La1-xSrx)2CuO4

Nuclear spin-lattice relaxation times T 1 of 139 La in high- T C superconductor (La 1- x Sr x ) 2 CuO 4 ( x =0.075, 0.10) have been measured in zero field. T 1 -1 in the superconducting state decreases rapidly, indicating a superconducting energy gap formation, but no signs of T 1 -1 enhancement are observed just below T C . T 1 -1 in the normal state shows slightly stronger temperature dependence than that expected from the Korringa relation ( T 1 T =const.) observed in a highly Sr-doped, nonsuperconducting compound with x =0.15.