Numerical evaluations on the asymmetric bias dependence of magnetoresistance in double spin filter tunnel junctions

Abstract

In double spin filter tunnel junctions, the spin information is generated and analyzed purely from the spin filtering effect with nonmagnetic electrodes. In this article we numerically evaluate the bias dependence of magnetoresistance in such tunnel junctions (nonmagnetic metal/spin filter/nonmagnetic insulator/spin filter/nonmagnetic metal), particularly in cases when different spin filter materials are utilized. A large magnetoresistance with nonmonotonic and asymmetric bias dependence is expected within the framework of Wentzel–Kramers–Brillouin approximation. We illustrate the systematic influence of tunnel barrier height, tunnel barrier thickness, and exchange energy splitting on magnetoresistance, particularly focusing on the asymmetric behavior of the magnetoresistance bias dependence.