Half-metallic Fe/sub 3/O/sub 4/ films for high-sensitivity magnetoresistive devices

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