Anisotropic nuclear relaxation in YBa2Cu3O7

Abstract

Data are presented for the magnetic susceptibility of Y${\mathrm{Ba}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_7$ and for the anisotropy of the copper nuclear spin-lattice relaxation time $T_1$ in the normal state for planar [Cu(2)] sites in this system. Using the Cu NMR shift to partition the susceptibility and estimate the density of states, we analyze the conventional enhanced Korringa model of $T_1$ contributions, finding it incapable of accounting for the anisotropy of the observed relaxation times. A localized spin-fluctuation picture is also discussed briefly.