Nuclear Spin-Lattice Relaxation of 63,65Cu at the Cu(2) Sites of the High Tc Superconductor YBa2Cu3O7-δ

Nuclear spin-lattice relaxation times T 1 of 63 Cu and 65 Cu in the Cu(2) sites of the high T c superconductor YBa 2 Cu 3 O 7-δ (δ≃0.1, T c =91 K) have been measured for the wide temperature range between 2.2 K and 300 K. The temperature dependence of 1/ T 1 in the normal state has been found to be the one unexpected for simple metals. The influences of antiferromagnetic spin fluctuations in the d–p bands in the Cu(2)–O layers are discussed. …