Tailoring the Asymmetric Magnetoimpedance Response in Exchange-Biased

Abstract

The dependence of the asymmetric magnetoimpedance (MI) response on the directions of both the magnetic field and the exchange bias is studied for an [Ni-Fe(60nm)/Ir-Mn(35nm)]×5 multilayer system. The antiferromagnetic (AFM) layers create an exchange bias that shifts both the hysteresis loop and the MI response of Ni-Fe; the strength of this coupling depends on the thicknesses of both the ferromagnetic layer and the AFM layer. Tuning the exchange-bias angle and the applied-magnetic-field direction provides a practical method to control the symmetry and the magnitude of the MI response. The observed asymmetric response can be attributed to the coexistence of two anisotropies, the induced exchange-bias anisotropy and the magnetocrystalline anisotropy. Both are distinct components of the exchange-coupled Stoner-Wohlfarth energy density that forms a basis for simulations within the conventional Landau-Lifshitz-Gilbert framework. The model reproduces the main features of the experimental results, providing a deeper understanding of the effect of the anisotropy components on the MI characteristic curve and ratio. The results can be used for the development of an asymmetric MI exchange-biased thin-film element in an autobiased linear-magnetic-field sensor.