Electronic structures of LiFePO4 and FePO4 studied using resonant inelastic x-ray scattering

We have studied LiFePO4 and its delithiated counterpart FePO4 using the resonant inelastic x-ray scattering (RIXS) and x-ray absorption techniques. Using Voigt peak fitting, we have found all unresolved RIXS transitions. These energy-loss features were then ascribed to band-to-band transitions by comparison to theoretical density of states (DOS) calculations. We have found that the DOSs of LiFePO4 and FePO4, as probed with the RIXS technique, agree very well with a theoretical description of the system that does not explicitly account for electron correlation effects. We propose that the interesting properties of LiFePO4 result from the presence of bound magnetic polarons.