Electron paramagnetic resonance of single-phase pellets of the high-T_{c} superconductor YBa_{2}Cu_{3}O_{7-x}

The Cu-local environment of the high-$T_c$ superconductor ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7\mathrm{-}\mathrm{x}}$ has been investigated in the bulk form by the electron-spin-resonance technique. Two nonequivalent ${\mathrm{Cu}}^{2+}$ ion sites are singled out in this orthorhombic superconducting phase all over the experimental temperature range (77–298 K). The density of the magnetic moments drops under temperature increase from liquid nitrogen up to the superconductive transition temperature, therein it tails off almost linearly.