NUCLEAR-SPIN-LATTICE RELAXATION OF LA-139 IN (LA1-XSRX)2CUO4

We report here the data of 139La nuclear spin-lattice relaxation times T1 taken from 4.2K to 275K in (La1−xSrx)2CuO4, concentrating on a region from x=0.075 (superconducting with highest Tc to x=0.15 (metallic). In the superconducting state of the compounds with x=0.075 and 0.10, T1−1 just below Tc decreases rapidly without any enhancement. In the metallic sample of x=0.15, T1 follows a Korringa law within our experimental range of 4.2-77K. On the other hand, in the normal state for x=0.075, T1−1 shows anomalous increase from 70K to ~150K and then levels off at high temperatures. This anomalous behavior is considered to be originated in a change of the density of state at the Fermi level near to the La sites, probably caused by the orthorhombic-to-tetragonal phase transition. © 1990, Elsevier Science Publishers B.V. (North-Holland). All rights reserved.