Study of CoFeSiB glass-covered amorphous microwires under applied stress

Magnetoimpedance-based ferromagnetic resonance (FMR) studies of annealed Co68.15Fe4.35Si12.5B15 glass-covered amorphous microwires under stress are reported. The applied stress modifies the anisotropy and the domain structure present in each sample, in such a way that it can be studied through magnetoimpedance measurements and FMR dispersion relations extracted from them. From the fitting of the FMR dispersion relations, the magnitude and the orientation of the transverse anisotropy field, as well as an insight on the micromagnetic structure of glass-covered microwires, were obtained. From these studies, it can be concluded that a longitudinal anisotropy dominates the microwire behavior under zero stress. By applying an increasing stress to the microwires, an inner core with a longitudinal anisotropy surrounded by an outer shell with a circumferential anisotropy develops and dominates its magnetic behavior. (c) 2005 American Institute of Physics.