Ion channeling in (Bi1.7Pb0.3)Sr2CaCu2Oxsingle crystals

Ion channeling, in combination with Rutherford backscattering spectrometry and measurements of characteristic x-ray production, was performed on single crystals of (${\mathrm{Bi}}_{1.7}$ ${\mathrm{Pb}}_{0.3}$)${\mathrm{Sr}}_2$ ${\mathrm{Ca}}_1$ ${\mathrm{Cu}}_2$ ${\mathrm{O}}_{\mathit{x}}$ at temperatures between 35 and 295 K. Substantial effects of the incommensurate lattice modulation on the channeling behavior were observed. In particular, the relatively large (≲0.03 nm) static atomic displacements from this modulation narrowed the critical angle for channeling by more than 50%, sharply reduced its expected temperature dependence, and increased the minimum yield by more than a factor of 3. Measurements of the critical angle as a function of temperature revealed an anomaly at ${\mathit{T}}_{\mathit{c}}$ (=90 K) in Cu-atom displacements perpendicular to the [001] axis. This anomaly appears to be identical to the one found previously in ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7\mathrm{-}\mathit{x}}$.