Nuclear quadrupole resonance and nuclear magnetic resonance of copper in the high-Tc superconductor YBa2Cu3O7−δ

Abstract

The ${}_{}{}^{65}{}_{}{}^{}\mathrm{Cu}$ and ${}_{}{}^{63}{}_{}{}^{}\mathrm{Cu}$ zero-field nuclear quadrupole resonance (NQR), nuclear magnetic resonance at 4.7 and 8.5 T, and the spin-lattice relaxation time $T_1$ at 8.5 T are measured in the superconducting oxide $\mathrm{Y}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-\delta }$ between 80 and 300 K. No sign of magnetic order or localized moments is found. The NQR linewidth is strongly dependent on the oxygen content. We assign the ${}_{}{}^{63}{}_{}{}^{}\mathrm{Cu}$ NQR line at 22 MHz to the Cu site with oxygen coordination 5; $T_1$ is dominated by the quadrupolar relaxation due to spin-phonon coupling.