Magnetic ordering at the Verwey transition in bulk like Fe3O4 thin films

Magnetite (Fe3O4) is a predicted half-metallic (100% spin polarised) ferromagnet with a high Curie temperature of ~858K. These properties make it well suited to use in spintronic applications such as magnetoresistance-based devices and spin injection into semiconductors. In bulk magnetite, the origin of the Verwey transition is still debated. However, thin film investigations of magnetite have been hindered by strain and growth defects leading to antiphase boundaries and altered magnetic properties. We have developed an optimised growth method for producing Fe3O4 thin films with bulk-like stoichiometry and properties. This provides a unique opportunity to study the magnetization depth dependence through the Verwey transition. The results will clarify the role of the interface and of strain on the density of defects, such as antiphase boundaries, and point the route to device fabrication.