Magnetite at low temperature: Resonant inelastic x-ray scattering (RIXS) at the Fe K-edge

At room temperature, magnetite (cubic inverse spinel structure, Fd-3m s.g.) shows metal-like electrical conductivity, which discontinuously drops by two orders of magnitude below ca. 120 K (Tv). This is due to a first-order phase transition, where the cubic structure is distorted to monoclinic symmetry (Cc s.g.). Models for this metal-insulator transition are still highly debated. We performed 1s3p as well 1s2p RIXS measurements well below and above Tv on a sample of synthetic magnetite powder to probe any difference present in the electronic states. Neither 1s3p nor 1s2p RIXS spectra reveal any differences between the two phases. Our observations are consistent with earlier EXAFS data and indicate no changes in the local structural geometry around Fe.