Diamagnetism in the normal state of ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_7$

Precise ${}_{}{}^{63}{}_{}{}^{}\mathrm{Cu}$ NMR shift results are reported for both copper sites in oriented powder samples of ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7.0}$, in which the weak normal-state temperature dependences are resolved. Magnetic-susceptibility data are also given, which, in spite of the presence of small Curie-like terms, are shown to have the same intrinsic temperature dependence as data recently presented by Lee, Klemm, and Johnston. A combined analysis of shift and susceptibility data is described, in which we obtain (1) a partition of the spin paramagnetism between the chain and plane sites, (2) a full description of the susceptibility and hyperfine interaction tensors based only on static measurements, and (3) extracted values for temperature-dependent diamagnetism under field orientation both along the c axis and in the ab plane. The c-axis diamagnetism is large and decays with temperature in a fashion consistent with the asymptotic ${\mathit{T}}^{\mathrm{-}1}$ behavior predicted in recent theories. In the ab plane, the diamagnetism sets on at T∼125 K in what appears to be a dimensional crossover from purely two-dimensional behavior at high temperatures. The analysis also suggests that the actual degree of bulk susceptibility anisotropy is slightly higher than experimentally reported values. The hyperfine parameters are not markedly changed from those given earlier by Mila and Rice.