Influence of metal magnetic state and metal-insulator-semiconductor structure composition on magnetoimpedance effect caused by interface states

This article presents the results of a study of the transport properties of metal/insulator/semiconductor (MIS) hybrid structures in alternating current (ac) mode. We prepared a series of samples with different layers of metal, insulator, and semiconductor. We prepared a series of samples with different layers of metal, insulator and semiconductor. Ferromagnetic Fe and non-magnetic Cu and Mn were chosen as metals, the insulators were SiO2 and Al2O3, and n- and p-type Si substrates were used as semiconductors. Temperature dependence of the real part of the impedance showed peculiar peaks below 40К for different combinations of metals, insulators and semiconductors. For all samples the effect of the magnetic field on the transport properties was studied. At low temperatures, the magnetic field shifts peaks toward higher temperatures. Metal magnetic state does not significantly affect this phenomenon. Changing the type of the insulator and its thickness also did not cause any significant effect. However, the effect was observed for samples with different composition. Moreover, the type of conductivity of the substrate, as well as the type of metal, determines the value of magnetoimpedance. The main role in the magnetoimpedance effect is played by recharge of the energy states localized at the insulator/semiconductor interface. This mechanism allows obtaining a MI effect even in “nonmagnetic” MIS structures; magnetoimpedance can be either positive or negative, depending on temperature and frequency. We suggest that the observed ac magnetotransport phenomena could be used for creating magnetic field sensors, working on new principles.