NMR RELAXATION IN Y-BA-CU-O SUPERCONDUCTORS

Nuclear magnetic resonance and nuclear quadrupole resonance have made significant contributions to the understanding of high-temperature superconductors (HTSC). In particular, spin-lattice relaxation studies have provided information on the dynamics in HTSC on an atomic scale. This paper discusses such studies in some typical HTSC of the Y-Ba-Cu-O family, such as YBa2Cu3O7-x, YBa2Cu4O8 and Y2Ba4Cu7O15 with many examples of investigations performed in the author's laboratory. The results are discussed with respect to various topics such as anti-ferromagnetic spin fluctuations and the presence of a spin-gap, quasi-particles, the coupling between planes and the spacial symmetry of the superconducting pair wave function.