Half-metallic Fe3O4 films for high-sensitivity magnetoresistive devices

By RF sputtering on a MgO (100) substrate, we have made Fe3O4 (111) metal and Fe3O4 (001)/TiN (001) films that have Verwey temperature (T-V) near 120 K. The saturation magnetizations and resistivities of those Fe3O4 films were comparable to those of bulk Fe3O4, and the magnetoresistive (MR) ratio and MR ratio area product ADeltaR measured for various materials structures of current perpendicular to plane (CPP) samples using Fe3O4 (111) increased sharply at 120 K. This increase around T-V seemed to be related to the change in the Fe3O4 crystal. The ADeltaR and MR of CPP-GMR samples using Fe3O4 (001), on the other hand, such as Ni80Fe20/TiN/Fe3O4 (001)/TiN (001), Co75Fe25/TiN/Fe3O4 (001)/TiN (001), and Fe3O4/TiN/Fe3O4 (001)/TiN (001), were 2-4 times larger than those of CPP-GMR samples using Fe3O4 (111) were. And for Fe3O4 (001) the increase of MR at T-V was smaller than it was for Fe3O4 (111).