Surface spin-transfer torque and spin-injection effective field in ferromagnetic junctions: Unified theory

TL;DR

This paper develops a unified theoretical approach to analyze the combined effects of spin-transfer torque and spin injection in ferromagnetic junctions, providing insights into their interaction and stability.

Contribution

It introduces a novel method to simultaneously calculate spin-transfer torque and spin injection effects in ferromagnetic junctions, including nonlinear steady-state analysis.

Findings

Derived dispersion relation for fluctuations.

Solved nonlinear steady-state problem.

Analyzed instability in thick free layers.

Abstract

We consider theoretically a current flowing perpendicular to interfaces of a spin-valve type ferromagnetic metallic junction. For the first time an effective approach is investigated to calculate a simultaneous action of the two current effects, namely, the nonequilibrium longitudinal spin injection and the transversal spin-transfer surface torque. Dispersion relation for fluctuations is derived and solved. Nonlinear problem is solved about steady state arising due to instability for a thick enough free layer.