Oxygen Content Dependence of Nuclear Resonance Spectrum in Tetragonal YBa₂Cu₃O_x

Abstract

The dependence of the resonance profiles for ⁶³Cu and ⁶⁵Cu on the oxygen content, x, in YBa₂Cu₃O_x (6.1≤x≤6.4) was investigated systematically. The measurements were performed for two different sites, the Cu–O₂ plane site (Cu(2)) and the Cu–O chain site (Cu(1)), at the liq. He temperature. The NQR spectrum corresponding to the Cu(1) sites consists of three different spectra. Their relative intensities change systematically with increasing x. Some discussions are made on the oxygen coordination, the spectral shift and the line broadening. The quadrupolar-split NMR spectra associated with the Cu(2) sites were obtained in x≤6.3. Although the magnetic line broadening becomes significant, no spectral shift was observed with the increase of x. This means that the magnetic moment on the Cu(2) site in the antiferromagnetic state does not change, at least until x=6.3.