Electronic structure near antiphase boundaries in magnetite

Abstract

Magnetite (Fe3O4) is a magnetic material with potentially interesting properties for applications in spintronics. The promising properties of this oxide are unfortunately affected by several kinds of structural defects which locally modify the electronic structure. We have calculated the density of states in the vicinity of the important defects which are the antiphase boundaries. The calculations have been performed with the LSDA+U approximation. This approximation is suitable to study transition metal oxides with important correlation effects between 3d electrons, as we have first shown for perfect bulk magnetite, by comparing the density of states calculated with the LSDA, LSDA+U, and PBE0 approximations. Our calculations show that antiphase boundaries are responsible for the existence of new localised electron states (defect states) which modify the electric properties, the energy gaps and the Fe magnetic moments.