Giant magneto-impedance in Co-rich amorphous wires and films

A comprehensive analysis of magneto impedance (MI) phenomena in Co-rich amorphous materials is presented on the basis of skin effect in combination with dynamical magnetization processes. We consider a MI effect for which the domain walls are perpendicular to the current and field direction. Thus, the magnetization induced by current proceeds, via both the wall movement and moment rotation. The magnetic responses of impedance in wires and films have some common features and can be understood from the same mechanism. The sensitivity of the magnetic response in a small sample (1 mm length and a few micrometer thickness) is about 10%/Oe in wires and 5%/Oe in films. The model describes well the existing experimental data for moderate frequencies, There is some quantitative discrepancy for the case of a very strong skin effect, where the position dependence of basic magnetostatic parameters is important.<>