Angular dependence of giant magnetoimpedance in an amorphous Co-Fe-Si-B ribbon

The field response of impedance is studied in a stress-annealed amorphous r ibbon as a function of the angle of application of the external magnetic fi eld in order to verify the role of induced anisotropies (and their distribu tion) and demagnetizing factors in the giant magnetoimpedance (GMI) phenome non which occurs in soft magnetic materials. The experimental results are w ell explained by a theoretical model, based on the simultaneous solution of Maxwell equations and the Landau-Lifshitz equation of motion. Demagnetizin g effects are properly taken into account in the case of ribbons or thin fi lms. The physical parameters necessary to test the theory were obtained thr ough complementary measurements of the ferromagnetic resonance and temperat ure dependence of magnetization. The results clearly indicate the enormous influence of the distribution of anisotropies on the GMI effect. Also, an e xperimental procedure for determining the easy-axis distribution function i s proposed. [S0163-1829(99)15433-X].