Cu63 NMR study of conducting delafossites

NMR data are presented for the conducting delafossites Y0.99Ca0.01CuO2.65 and LaCuO2.64. These materials exhibit a planar structure with triangular arrays of exchange-coupled S=1/2(Cu2+) spins. The two compounds examined show strikingly different quadrupole-broadened NMR powder patterns, which is evidence for different in-plane arrangements of O2- ions. Their doped-hole carrier densities are comparable to those of the superconducting cuprates. In consequence, they have Korringa-like T1 processes. We also find evidence for dynamic Jahn-Teller motion and ferromagnetic Benhancement of the spin paramagnetism for Y0.99Ca0.01CuO2.65. T2 studies indicate that the strong antiferromagnetic fluctuation effects found in the superconducting cuprates are absent.