CU-63 NUCLEAR-SPIN-LATTICE RELAXATION STUDY FOR LOW-TEMPERATURE STRUCTURAL TRANSITION IN (LA1-XBAX)2CUO4 AROUND X=0.06

The nuclear spin-lattice relaxation rate 1/T1 of CU-63 was measured in the range from 1.5 to 300 K for x=0.0625 and x=0.08 in (La1-xBax)2CuO 4. In the high-temperature tetragonal (HTT) and the low-temperature or thorhombic (LTO) phases in the normal state, 1/T1T for both samples fo llows the Curie-Weiss law, C/(T + theta), suggesting that the two-dime nsional (2D) antiferromagnetic (AF) fluctuation among Cu spins is domi nant, similarly to the (La1-xSrx)2CuO4 system. In the HTT and LTO phas es, no significant differences except for a slight difference in theta were observed between the two samples. In the low-temperature tetrago nal (LTT) phase for x=0.0625, 1/T1 diverges at about 35 K, confirming the existence of magnetic ordering. The magnetic ordering at the finit e temprature suggedsts that the dominant 2D-AF correlation of Cu spins in the HTT or LTO phase becomes the 3D-AF correlation derived from th e some interactions along the c axis in the LTT phase.