Electronic structure and polaronic excitation in FeVO4

We investigated the electronic properties of FeVO4 films using optical, valence band x-ray photoelectron, and infrared spectroscopies. These studies show that FeVO4 is a direct bandgap system with a 2.7 eV gap with the Fermi level in the middle of the valence band maximum and conduction band minimum. A polaronic excitation is also observed in the middle infrared, indicating the importance of charge-lattice coupling in this multiferroic material. Fits to a model for the optical response of large polarons yield a binding energy of approximately 130 meV. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3646402]