Copper NMR and hole depletion in the normal state of Y1-xPrxBa2Cu3O7

Normal-state copper NMR spectra and spin-lattice relaxation rates 1/T1 have been measured in the planar cuprate system YBa2Cu3O7. With Pr doping the Knight shift K decreases and develops a temperature dependence at both plane and chain sites. Analysis of the bulk susceptibility and NMR data indicate that pair breaking and hole depletion both take part in the suppression of the superconducting transition temperature Tc. The Knight shift behavior resembles that in oxygen-deficient YBa2Cu3O7-y, as does the temperature dependence of 1/T1 for plane Cu sites and magnetic field perpendicular to the c axis. This agreement leads to a consistent picture of the role of antiferromagnetic fluctuations in these materials. An analysis of the data in the framework of the phenomenological theory of Millis, Monien, and Pines is given. In the end compound PrBa2Cu3O7 the NMR signal from plane Cu sites indicates antiferromagnetic (AF) ordering at a Neel temperature ∼280 K, and in the AF state yields an internal field similar to those found in AF YBa2Cu3O6 and La2CuO4. 32 refs., 7 figs