A model for asymmetric magnetoimpedance effect in multilayered bimagnetic films

• A model for asymmetric magnetoimpedance in three-layered bimagnetic film is proposed.
• Asymmetry in magnetoimpedance is related to magnetostatic coupling between magnetic layers.
• Bias field in soft magnetic layer changes static magnetization distribution.
• Magnetoimpedance is analyzed as a function of bias field and anisotropy axis angle.
• Results of modeling describe qualitatively experimental data obtained previously.

The magnetoimpedance in three-layered bimagnetic film structure is studied theoretically. The structure consists of the soft and hard magnetic films separated by highly conductive non-magnetic layer. A model to describe the magnetoimpedance effect in the film structure based on a simultaneous solution of linearized Maxwell equations and Landau–Lifshitz equation is proposed. It is shown that magnetostatic coupling between the magnetic layers results in the asymmetry in the field dependence of the film impedance. The magnetostatic coupling is described in terms of an effective bias field appearing in the soft magnetic layer. The calculated field and frequency dependences of the film impedance are shown to be in a qualitative agreement with previous results of experimental studies of the asymmetric magnetoimpedance in NiFe/Cu/Co film structures. The results obtained may be useful for development of weak magnetic-field sensors.