Anomalous behavior of thermal vibrations of atoms as a result of the phase transition of Tl2Ba2CaCu2O8 single crystals to the superconducting state
Simonov V. I., Molchanov V. N., Merisalo M. Yu., Blomberg M. K.
An x-ray diffraction analysis reveals that structural parameters of a (Tlo^Cuo^hBaz(CaoggTlo.n) Cu2Os single crystal with Tc= 100 К behave in an anomalous way as a result of a phase transition to the superconducting state. The anomalous temperature dependence is seen particularly clearly in parameters of thermal vibrations of atoms. It thus becomes possible to draw conclusions about the changes in the valence state and the chemical bonds (i.e., the electronic structure) of atoms in the crystal upon the phase transition. Substantial changes in the phonon spectrum in the course of this phase transition are indicated.