Details of the electronic superstructure of Fe3O4

Abstract

After introducing briefly the derived electronic superstructure of Fe304, recent advances in the model are explained. The transition may be described as the ordered microsegregation of the linked molecular pseudo-metallic units. Mössbauer results predicted that the population ratio of Fe2+−II to Fe2+−I is 3:5 in contrast to 4:4 of the previous understanding and all the results are consistently understood by assuming that all the Fe2+ ions have a Jahn-Teller stabilized dεξη orbital for the additional electron. We observed ferroelectric hysteresis curves at 4.2 K with the saturation polarization of about 0.8 μC/cm2 along the c axis. The importance of strains in the metal-insulator electronic transition in general is pointed out and the term ’’releasing the microscopic strain by antiphases’’ is emphasized, which may replace the term ’’incommensurable charge density wave’’ in many cases.