Ion-channeling anomalies at the superconducting transition temperature in single-crystal ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_{7\mathrm{-}\mathrm{y}}$

The temperature dependence of the Rutherford backscattering in the 〈001〉 axial channeling mode for each constituent atom of single-crystal ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7\mathrm{-}\mathrm{y}}$ has been carried out to study a change in the structural properties at the superconducting transition. Anomalies of channeling behavior observed across the superconducting transition temperature suggest a structural instability or a change in the lattice. The anomalies of channeling for Y and Ba atoms suggest the phonon softening, while those for Cu and O atoms are not explained in terms of only the phonon softening, but probably indicate complicated lattice dynamics of Cu and O atoms.