Exchange anisotropy in reactively sputtered amorphous CoFeSiB:O thin films

Exchange-shifted hysteresis loops were observed at 300 K in thin amorphous films deposited from a CoFeSiB alloy target by reactive oxygen sputtering. The heterogeneous film morphologies consisted of nanoscale features with thin, apparently oxidized, boundaries, The exchange shift varied with the film thickness, and with the ratio of the oxygen to argon gas flow, The CoFeSiB:O films exhibiting exchange anisotropy had resistivities in the range /spl sim/10/sup 3/ /spl mu//spl Omega//spl middot/cm to /spl sim/10/sup 4/ /spl mu//spl Omega//spl middot/cm. The maximum shift (/spl sim/10 Oe) was observed in films with a resistivity of /spl sim/2500 /spl mu//spl Omega//spl middot/cm. The exchange anisotropy appears to be due to coupling between nanoscale regions with different coercivities.