Soft bilayer alloys were produced by depositing granular Fe: SiO2 onto transition-metal thin films. We have prepared series of samples using different soft-magnetic materials including permalloy (Ni80 Fe20), hcp Co90 Fe10, and amorphous Co60 Fe20 B20, all covered by a layer of superparamagnetic Fe particles in a silicon-oxide matrix. The thickness of transition-metal layer was fixed and the magnetic properties of the bilayer system were studied by varying the Fe: SiO2 layers thicknesses from 0 to 70 nm. The bilayer yields a moderate improvement of the soft-magnetic performance. The hysteresis loops show a pronounced twofold anisotropy in the film plane for permalloy and amorphous CoFeB, which is consistent with the presence of external magnetic field during processing. This indicates that the coercivity is controlled by the pinning of 180° domain walls and that the effect of the Fe particles on the hysteresis is mediated by the interaction with the domain-wall stray fields.
ASJC Scopus subject areas
- Physics and Astronomy(all)