Asymmetric Bias Dependence in Double Spin Filter Tunnel Junctions

TL;DR

This paper investigates how bias voltage affects magnetoresistance in double spin filter tunnel junctions with nonmagnetic electrodes, revealing asymmetric and nonmonotonic behaviors influenced by material properties.

Contribution

It provides a numerical analysis of bias dependence in double spin filter tunnel junctions, highlighting the asymmetric effects due to different material parameters and barrier properties.

Findings

Magnetoresistance shows nonmonotonic bias dependence.

Asymmetry in bias dependence is influenced by barrier height and exchange energy.

Systematic effects of barrier thickness on magnetoresistance are demonstrated.

Abstract

In double spin filter (SF) tunnel junctions, the spin information is generated and analyzed purely from the SF effect with nonmagnetic electrodes. In this article we numerically evaluate the bias dependence of magnetoresistance in such tunnel junctions (nonmagnetic metal / SF / nonmagnetic insulator / SF / nonmagnetic metal), particularly in cases when different SF materials are utilized. A large magnetoresistance with nonmonotonic and asymmetric bias dependence is expected within the frame of WKB 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.