Experimental and phenomenological investigation of the effect of stress on magneto-impedance in amorphous alloys

The tensile stress dependence of magneto-impedance (MI) in CoSiB and CoFeSiB amorphous wires is reported. A phenomenological model for the transverse susceptibility based on a simple domain structure, and which includes the magneto-elastic energy contribution, is used. The square-root of the transverse susceptibility is assumed to be proportional to the magneto-impedance. The model predicts correctly the form of the stress dependence of the MI-effect, and shows that a significant distribution in the magnitude of the anisotropy constant is needed to explain the MI-response of these wires. Modelling also suggests that at higher excitation frequencies (greater than or equal to 1 MHz) magnetic moment rotation is the dominant process controlling the MI-effect.