First-principles study of magnetization relaxation enhancement and spin-transfer in thin magnetic films

TL;DR

This study uses first-principles calculations to analyze how interfaces in thin ferromagnetic films affect magnetization damping and spin transfer, revealing that interface effects dominate these phenomena with minimal interference effects.

Contribution

It provides a detailed first-principles analysis of interface-induced magnetization damping and spin transfer in thin ferromagnetic films, highlighting the small interference effects and the real-valued nature of mixing conductances.

Findings

Interference effects are very small due to short magnetic coherence length.

Spin pumping can be modeled by increased Gilbert damping without changing gyromagnetic ratio.

Spin-current induced torque is primarily an interface phenomenon.

Abstract

The interface-induced magnetization damping of thin ferromagnetic films in contact with normal-metal layers is calculated from first principles for clean and disordered Fe/Au and Co/Cu interfaces. Interference effects arising from coherent scattering turn out to be very small, consistent with a very small magnetic coherence length. Because the mixing conductances which govern the spin transfer are to a good approximation real valued, the spin pumping can be described by an increased Gilbert damping factor but an unmodified gyromagnetic ratio. The results also confirm that the spin-current induced magnetization torque is an interface effect.