On the optical properties and low pressure-induced spin transition in magnetite from ab initio calculations

The electrical anomaly observed in the high-temperature phase of magnetite under pressure is studied in the framework of DFT/LSDA+U formalism. We show that the phenomenon cannot be accounted for by a coordination crossover nor by a Fe 2 + high-spin (HS) to an intermediate-spin (IS) transition. We suggest the transition may be related to the formation of an inhomogeneous mixed-spin state system HS → HS / LS with cations in octahedral sites.