Film structures of Fe/B-doped carbon/Fe₃Si spin valve junctions

Fe/B-doped carbon/Fe3Si trilayered films were prepared on Si(111) substrates by physical vapor deposition with a mask method, and the film-structures and magnetic properties of the films were investigated. The Fe3Si and Fe layers were deposited by facing targets direct-current sputtering (FTDCS), and the B-doped carbon layers were deposited by coaxial arc plasma deposition (CAPD) with B-blended graphite targets. Here, since the B-doped carbon layers were deposited by CAPD in the same manner as the deposition of B-doped ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) films, the interlayers should be B-doped UNCD/a-C:H. The formation of a layered structure was confirmed by transmission electron microscopy (TEM). The diffusion of Fe and Si atoms into the interlayer occurs in the range of several nanometers. The shape of the magnetization curve has clear steps that evidently indicate the formation of antiparallel alignment of magnetizations owing to the difference in the coercive forces between the top Fe and bottom Fe3Si layers. It was experimentally demonstrated that B-doped UNCD/a-C:H is applicable to Fe–Si system spin valves as interlayer materials.