Site assignment for copper nuclear-quadrupole-resonance lines in YBa2Cu3O7- delta.

Abstract

Data on the $^{63}\mathrm{Cu}$ nuclear-magnetic-resonance intensity in powdered ceramic samples of Y${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ are analyzed to yield the relative and absolute intensities of the Cu(1) and Cu(2) sites, using similar data on $^{63}\mathrm{Cu}$ in ${\mathrm{Cu}}_{2}$O as a reference standard. These data confirm the assignment of the 31.48 MHz nuclear-quadrupole-resonance line to the Cu(2) (planar) sites and the 22.05 MHz line to the Cu(1) (chain) sites mandated by recent experiments at other laboratories. Relaxation data for $^{89}\mathrm{Y}$, also presented, may reflect antiferromagnetically correlated spin fluctuations in the planes.