Half-Metallic>tex /tex<Films for High-Sensitivity Magnetoresistive Devices

By RF sputtering on a MgO (100) substrate, we have made Fe 3 O 4 (111) metal and Fe 3 O 4 (001)/TiN (001) films that have Verwey temperature (T V ) near 120 K. The saturation magnetizations and resistivities of those Fe 3 O 4 films were comparable to those of bulk Fe 3 O 4 , and the magnetoresistive (MR) ratio and MR ratio area product AΔR measured for various materials structures of current perpendicular to plane (CPP) samples using Fe 3 O 4 (111) increased sharply at 120 K. This increase around T V seemed to be related to the change in the Fe 3 O 4 crystal. The AΔR and MR of CPP-GMR samples using Fe 3 O 4 (001), on the other hand, such as Ni 80 Fe 20 /TiN/Fe 3 O 4 (001)/TiN (001), Co 75 Fe 25 /TiN/Fe 3 O 4 (001)/TiN (001), and Fe 3 O 4 /TiN/Fe 3 O 4 (001)/TiN (001), were 2-4 times larger than those of CPP-GMR samples using Fe 3 O 4 (111) were. And for Fe 3 O 4 (001) the increase of MR at T V was smaller than it was for Fe 3 O 4 (111).