Phonon Dynamics in Parent and Superconducting FeAs Compounds

R. Mittal ； M. Zbiri ； S. Rols ； Y. Su ； Y. Xiao ； S. L. Chaplot ； H. Schober ； M. Johnson ； T. Chatterji ； S. Matsuishi ； H. Hosono ； T. Brueckel

《Chinese Journal of Physics》 49卷1期 (2011/02) Pp. 403-413

並列摘要

The comparison of the phonon spectra of the parent MFe2As2 (M=Ba, Ca, Sr) and MFeAsF (M=Ca, Sr) compounds show a very strong renormalization in the lower and intermediate frequency part of the vibrations. Mass effects and lattice contraction cannot solely explain these changes. Further, the measurement of temperature dependence of phonon density of states across the magnetic/structural phase transition temperature indicates that softening of low energy modes in the paramagnetic state of these compounds may be due to the interaction of phonons with electron or short-range spin fluctuations in the normal state of the superconducting compound as well as in the parent compound. Detailed lattice dynamical calculations are carried out to analyze the experimental data.