Interface enhancement of Gilbert damping from first-principles

TL;DR

This paper uses first-principles scattering theory to quantitatively analyze how interfaces with non-magnetic metals enhance Gilbert damping in Ni80Fe20 films, emphasizing the role of interface spin-flipping.

Contribution

It generalizes the spin-pumping theory to include interface effects and determines key parameters from first-principles calculations, highlighting the importance of interface spin-flipping.

Findings

Interface spin-flipping significantly contributes to damping enhancement.

The calculated spin-flip diffusion length for Pt aligns with experimental values.

The theory accurately reproduces experimental damping enhancements.

Abstract

The enhancement of Gilbert damping observed for Ni80Fe20 (Py) films in contact with the non-magnetic metals Cu, Pd, Ta and Pt, is quantitatively reproduced using first-principles scattering theory. The "spin-pumping" theory that qualitatively explains its dependence on the Py thickness is generalized to include a number of factors known to be important for spin transport through interfaces. Determining the parameters in this theory from first-principles shows that interface spin-flipping makes an essential contribution to the damping enhancement. Without it, a much shorter spin-flip diffusion length for Pt would be needed than the value we calculate independently.