Local magnetization processes at constricted regions in amorphous Fe80B20 stripes with nanometric thicknesses

Results are presented on the dependence of the coercivity and reduced remanence on the dimensions of constrictions engraved by UV lithography in long aspect ratio stripes having a few tens of microns widths and 20 nm thicknesses. Our data cover the hysteretic behavior both away and close to the constrictions and obtained by applying dc fields along the long stripe axis and perpendicularly to it. We conclude that it is possible obtain, at narrow constrictions involving large stripe width reductions and by applying transverse fields, local reduced remanences close to 1.0 associated to coercivities above 20 Oe, which is compatible with the stabilization, in the coercivity field range, of the local magnetization at the constriction in a direction close to perpendicular to the stripe long axis