Study of magnetization processes in amorphous ferromagnetic alloys after heat treatment below the crystallization temperature

In this work we studied magnetization processes in the amorphous ferromagnetic Fe73.5Cu1Nb3Si13.5B9 alloy (FINEMET precursor) after subcritical annealing below its primary crystallization temperature. Basic measurements of effective anisotropy and coercivity showed that such thermal processing causes significant changes in its total magnetic anisotropy, domain wall width and energy per unit area. Analysis of these values led to conclusion that these changes are caused by modification of internal stress areas, which alters the mobility of domain walls. We took into consideration the impact of mechanical load on total demagnetizing factor as well. It was separated into three components: the external factor Dg, the internal factor originating from existing clusters Dcl, and the internal factor originating from magnetic inhomogeneities caused by internal stresses D sigma. We concluded that the main reason behind the changes of magnetic properties of the studied alloy after subcritical annealing are changes of stress areas due to relaxation effects.