Measurement of Anomalous Phonon Dispersion of CaFe_2As_2 Single Crystals Using Inelastic Neutron Scattering

摘要

We measured phonon dispersions of CaFe_2As_2 using inelastic neutron scattering and compared our results to predictions of density functional theory in the local density approximation. The calculation gives correct frequencies of most phonons if the experimental crystal structure is used, except observed linewidths/frequencies of certain modes were larger/softer than predicted. Strong temperature dependence of some phonons near the structural phase transition near 172 K may indicate strong electron-phonon coupling and/or anharmonicity, which may be important for superconductivity.