Spin Transfer Torque with Spin Diffusion in Magnetic Tunnel Junctions

TL;DR

This paper presents a theoretical study of spin transfer torque in magnetic tunnel junctions, highlighting how spin diffusion influences the bias dependence and thickness behavior of spin torque components.

Contribution

It introduces a combined ballistic and diffusive model to analyze spin dynamics, revealing new effects of spin diffusion on torque behavior in magnetic tunnel junctions.

Findings

Spin diffusion mixes transverse spin current components.

Bias dependence of out-of-plane torque becomes significantly linear.

Thickness dependence of spin torque components is non-conventional.

Abstract

Spin transport in magnetic tunnel junctions in the presence of spin diffusion is considered theoretically. Combining ballistic tunneling across the barrier and diffusive transport in the electrodes, we solve the spin dynamics equation in the metallic layers. We show that spin diffusion mixes the transverse spin current components and dramatically modifies the bias dependence of the effective spin transfer torque. This leads to a significant linear bias dependence of the out-of-plane torque, as well as a non-conventional thickness dependence of both spin torque components.