Bias voltage dependence of tunnel magnetoimpedance in AlOx-based magnetic tunnel junctions

This paper studies the bias voltage dependence of tunnel magnetoimpedance in two types of AlOx-based magnetic tunnel junctions (i.e., CoFeB/AlOx/CoFeB and CoFeB/AlOx). The impedance spectra methodology is applied to characterize the transport properties and barrier/interface behavior of the tunnel junctions. The bias voltage dependence of the impedance spectra shows different behaviors for each type of junction, thus contributing different physical parameters to the equivalent circuit model. The results indicate that the interplay of the spin dynamics and dielectric relaxation may be attributed to the magnetic tunnel dynamics. The physical parameters obtained from the equivalent circuit analysis provide information on the spin-dependence tunnel junctions for devices applications.