Effect of Spin-Flip Scattering on Electrical Transport in Magnetic Tunnel Junctions

TL;DR

This paper investigates how spin-flip scatterings affect electrical transport in magnetic tunnel junctions using nonequilibrium Green function techniques, revealing modifications to conductance formulas and explaining experimental anomalies.

Contribution

It introduces a modified conductance model accounting for spin-flip scatterings and explains experimental observations of resistance behavior in FM-I-FM junctions.

Findings

Spin-flip scatterings cause an angular shift in tunnel conductance.

The junction resistance can be maximum at non-antiparallel orientations.

Spin-flip assisted tunneling is observed.

Abstract

By means of the nonequilibrium Green function technique, the effect of spin-flip scatterings on the spin-dependent electrical transport in ferromagnet-insulator-ferromagnet (FM-I-FM) tunnel junctions is investigated. It is shown that Julliere's formula for the tunnel conductance must be modified when including the contribution from the spin-flip scatterings. It is found that the spin-flip scatterings could lead to an angular shift of the tunnel conductance, giving rise to the junction resistance not being the largest when the orientations of magnetizations in the two FM electrodes are antiparallel, which may offer an alternative explanation for such a phenomenon observed previously in experiments in some FM-I-FM junctions. The spin-flip assisted tunneling is also observed.