Raman-scattering study of misfit-layered (Bi, Pb)-Sr-Co-O single crystal

Abstract

Polarized Raman scattering measurements were performed on misfit-layered thermoelectric Bi2-x Pbx Sr2 Co2 Oy (x=0.6) single crystal from 20 K to room temperature. Four peaks were observed in the parallel polarization channel and no peaks in the cross polarization channel. One of the Raman peaks carries the asymmetric characteristic, which can be regarded as an evidence of the existence of electron-phonon coupling. Furthermore, the asymmetric parameter, proportional to the strength of electron-phonon coupling, was estimated with the asymmetric Breit-Wigner-Fano line shape. The electron-phonon coupling may play an important role in understanding the large thermoelectric power of cobalt based materials. © 2007 American Institute of Physics.