Asymmetrical Magnetoimpedance Effect in Partially Devitrified Co₆₆Fe₄Si₁₆B₁₂Mo₂ Ribbons

Partial devitrification of Co₆₆Fe₄Si₁₆B₁₂Mo₂ amorphous ribbons leads to a magnetically hard-soft system that presents an anomalous magnetoimpedance (MI) effect as is reported in this work. The MI versus longitudinal dc magnetic field curves are asymmetrical, appearing horizontally shifted. The experiments prove that this shift can be tuned submitting the sample once to the adequate magnetic field. The evolution of the MI curves is here analyzed as a function of the amplitude and frequency of the excitation current, the previous constant magnetic field intensity and the maximum value of the magnetic field applied to trace them. The results suggest an interpretation of the phenomenon as the consequence of the modification of the internal magnetic field by the dipolar field created by the hard phase of the system, the crystallites, in the soft one, the residual amorphous matrix.