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 Y1-xPr(x)Ba2Cu3O7. The Knight shift K decreases with Pr doping and develops a temperature dependence at chain sites. Analysis of the bulk susceptibility and NMR data indicates that pair breaking and hole depletion both take part in the suppression of the superconducting transition temperature T(c). 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 approximately 280 K, and in the AF state yields and internal field similar to those found in AF YBa2Cu3O6 and La2CuO4.