Lattice dynamics of multiferroic BiFeO 3 studied by inelastic x-ray scattering

Abstract : We report an experimental study of the phonon dispersion in BiFeO(3) single crystals at ambient conditions by inelastic x-ray scattering (IXS). The phonon dispersions were recorded along several symmetry directions up to 35 meV. Our results compare favorably with first-principles calculations performed using density functional theory (DFT) within the local-density approximation (LDA). We resolve a discrepancy concerning the symmetry of the optical phonon branches observed by Raman spectroscopy, determine the energy of the lowest Raman and infrared silent mode, and derive a subset of the elastic moduli of BiFeO(3).