Crystallization and magnetic properties of FeCo/Si multilayer

Triode sputtering is used to fabricate polarizing monochromators and supermirrors for neutrons with high quality. X-ray, polarized neutron scattering, in situ ellipsometry and SQUID are used to investigate the growth of sputtered FeCo–Si multilayer to determine the crystallization and its influence on magnetic properties. The surface energy during the layer deposition is found to have the most important influence on crystallinity. High energy on the substrate achieved with argon bombardment at a substrate bias potential of −70 V produces a pronounced crystallinity of Fe89Co11 layers and facilitates chemical bond in the interface. On the contrary low energy on substrate under bias potential +100 V and floating results in low crystallinity and no chemical bond. In a XRD study on monochromators deposited at a bias potential of −70 V, the (1 1 0) plane of Fe89Co11 is observed with nearly hundredfold intensity compared to the one with bias potential of +100 V or floating potential. In addition, the magnetic properties of the monochromators are influenced with the bias voltage as well. The minus bias potential leads to high coercivity but reduced remanence compared with floating. The monochromator with a positive bias potential of +100 V shows distinct magnetic anisotropy and in its soft direction a magnetic remanence of 94%.