Influence of spin-orbit couplings to nuclear spin-lattice relaxation ratesin Sr-doped La2CuO4

The electronic structure of Sr-doped La2CuO4 has been investigated by means of cluster calculations. The results indicate changes in the energies of t he molecular orbitals when a copper atom is in the neighborhood of a Sr; in particular, the spin-orbit coupling is altered. It is shown that the Cu nu clear spin-lattice relaxation time depends crucially on this coupling when measured along the direction perpendicular to the CuO2 planes. II is argued that the results presented here are compatible with recent experimental ob servations.