Electronic structures ofLiFePO4andFePO4studied using resonant inelastic x-ray scattering

We have studied ${\mathrm{LiFePO}}_{4}$ and its delithiated counterpart ${\mathrm{FePO}}_{4}$ 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 ${\mathrm{LiFePO}}_{4}$ and ${\mathrm{FePO}}_{4}$, 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 ${\mathrm{LiFePO}}_{4}$ result from the presence of bound magnetic polarons.