Electronic processes in magnetite (or, “Enigmas of magnetite”)

The properties of magnetite in the region of the low-temperature transformation $T_t$=100–120 K are in many respects still unclear and even enigmatic, in spite of the enormous number of studies that have been undertaken over the years. In this review article a new model for the low-temperature transformation in magnetite is presented, based on an examination of the features of the temperature and field dependence of the spontaneous magnetization, magnetoresistance, and magnetocaloric effect and an analysis of the anomalies of electronic origin in the magnetic anisotropy and magnetostriction and the accompanying anomalies in the technical magnetization characteristics in the $T_t$ region. This “magnetic-electronic” model of the transition is consistent with experimental facts that do not fit into the well-known Verwey model of a “structural-electronic” transition.