AnisotropicCu63nuclear relaxation in magnetically oriented powdered samples ofYBa2Cu3O7

Planar-site ${}_{}{}^{63}{}_{}{}^{}\mathrm{Cu}$ nuclear spin-lattice relaxation data are presented for a magnetically oriented sample ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_7$ microcrystallites at temperatures 86 K≤T≤290 K and with the collective c axis at θ=0 and π/2 relative to the applied field. These results yield a relaxation anisotropy in good agreement with previous data obtained with random powders. The anisotropy exhibits a small temperature dependence, suggesting the presence of dynamical correlations among the Cu(2) 3d spins.