Control of Interface Structure for Oxides Artificial Lattices

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As one of the method for fabricating oxides artificial super lattices, alternative reactive sputtering method by using some metal targets is expected to be useful. We performed the basic investigation of deposition and oxidization of iron oxides thin films from an iron target by using Ar and Oxygen. From the XANES (X-ray absorption near edge structure) measurements, iron oxide thin films are containing Fe_3O_4 and gamma-Fe_3O_4 for the films sputtered under 4mTorr of oxygen partial pressure. The films sputteredunder 10mTorrof oxygen mainly consist of alpha-Fe_3O_4. We found a big magnetoresistive effect in the films which also show a high specific resistivity. This magnetoresistive effect is as large as 4% and it is about ten times big as the value for conventional bulk Fe_3O_4. From the structural analysis by using a transmission electron microscope, the films show a culumnar structure of Fe_3O_4 and its diameter is roughly 30-40nm.On the other hand, as one of the real multilayrs of oxides, we designed the multilayr structures of Bi-substituted iron garnet films for the purpose of megneto-optical recording media. The films are designed for having perpendicular magnetic anisotropy by utilizing the reverse magnetostrictive effect caused by the lattice mismatch between the layrs.