Multiple spintronic functionalities into single zinc-ferrous ferrite thin films

The ability to combine multiple spintronic properties in the ZnxFe3-xO4 system with different variants of its chemical composition offers a new and tantalizing route towards homodevices. This is mainly due to the advantage of varying the Zn component of ZnxFe3-xO4, which leads to the possibility of preserving spinel symmetry (within 5% lattice mismatch) while changing the material properties from a ferrimagnetic half-metal (x = 0) to an insulating paramagnet (x = 1). Here we demonstrate that ZnxFe3-xO4 thin films, grown from a ZnFe2O4 single phase target, laser-ablated under a reduced atmosphere, exhibits a reduction of Zn content, a large 4πMS (6.5 kG), very low resistivity (25 mΩ cm) and a Verwey transition, all of which can be engineered by an appropriate choice of growth temperature. All these spectacular properties are confirmed by ab initio calculations and can be attributed to the inverse structure of [Znx+2Fe1−x+3]A[Fe1+y+3Fe1−y+2]BO4-δ, where the reduced Fe+2 ions along with Fe+3 occupy the octahedral sites while the Zn+2 and inverted Fe+3 sit in the tetrahedral sites. Phase formation in laser ablated ZnxFe3-xO4 thin films are different compared to the bulk thermal equilibrium, and shows that there is a competition between the reduction of Zn and the formation of O vacancies at various growth temperature zones.