Reduction of the zero-phonon 57Fe Mössbauer fraction just above Tc in the (Bi,Pb)2Sr2Ca2Cu3O10 superconductor.

Abstract

A decrease of the zero-phonon fraction of the $^{57}\mathrm{Fe}$ M\"ossbauer absorption was observed in the temperature range 93--120 K in an Fe-doped (Bi,Pb${)}_{2}$${\mathrm{Sr}}_{2}$${\mathrm{Ca}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{10}$-type high-temperature superconductor indicating an anomalous behavior of the lattice vibrations. The isomer shift changes slightly in the same temperature range. The absence of a Goldanskii-Karyagin effect shows that the Fe mean-square displacement is isotropic. Between 150 and 550 K, the temperature dependence of the zero-phonon fraction follows a Debye model with a M\"ossbauer Debye temperature of 350 \ifmmode\pm\else\textpm\fi{}20 K.