Unconventional Hall effect in metal/semiconductor hybrid spintronic devices

Abstract

We investigate the Hall resistance of metallic multilayers Ta/Cr/CoTb/Ta/Si. In addition to the anomalous Hall effect originating from the ferrimagnetic CoTb layer, the unconventional Hall effect (UHE) is observed in our multilayer samples. The UHE depends not only on the current and magnetic fields but also on the device geometry and temperature in a unique way. Our results suggest that the UHE does not originate from the spin-orbit torque driven magnetization tilting but occurs possibly due to thermionic emission and Lorentz force at the metal/Si interface, where the Schottky barrier is formed. We also find that the space-charge effect causes geometric dependence of the Hall resistance. The magnitude of UHE is sizable and linearly proportional to the longitudinal magnetic field, suggesting that the observed UHE is attractive to the magnetic-field sensing industry.