Magnetic susceptibility anisotropy of grain-aligned oxygen-deficient Y₁Ba₂Cu₃O_x (6.46{slanted equal to or less-than}x{slanted equal to or less-than}6.98)

The anisotropic susceptibility of YBa₂Cu₃O_x (6.46{slanted equal to or less-than}x{slanted equal to or less-than}6.98) has been measured as a function of oxygen composition. Samples were prepared by a high temperature zirconium-getter annealing technique followed by magnetic orientation in epoxy. The normal state magnetic susceptibility was found to be weakly dependent on temperature. The room temperature values of the susceptibility decrease linearly as the oxygen composition decreases, whereas the difference in susceptibilities for magnetic fields parallel and perpendicular to the c-axis is nearly constant. This suggests that in this range of oxygen composition the susceptibility anisotropy comes mostly from the anisotropic part of the Van Vleck susceptibility and the spin susceptibility remains nearly isotropic. Neutron diffraction results show a significant oxygen occupancy at the O(5) site. Nuclear quadrupolar and magnetic resonance spectra of the plane copper indicate a marked degree of electronic disorder, confirming that there are microscopic structural effects from the high temperature zirconium-getter annealing procedure.