Magnetic properties in ultra-thin 3d transition metal alloys II: Experimental verification of quantitative theories of damping and spin-pumping

TL;DR

This study experimentally verifies theoretical models of damping and spin-pumping in disordered 3d transition metal alloys, providing quantitative analysis of intrinsic and extrinsic damping contributions across alloy compositions.

Contribution

It offers the first comprehensive experimental validation of quantitative theories of damping and spin-pumping in disordered 3d transition metal alloys.

Findings

Good agreement between experimental damping and theoretical calculations

Quantified extrinsic damping contributions including spin pumping and radiative damping

Identified compositional dependence of spin mixing conductance

Abstract

A systematic experimental study of Gilbert damping is performed via ferromagnetic resonance for the disordered crystalline binary 3d transition metal alloys Ni-Co, Ni-Fe and Co-Fe over the full range of alloy compositions. After accounting for inhomogeneous linewidth broadening, the damping shows clear evidence of both interfacial damping enhancement (by spin pumping) and radiative damping. We quantify these two extrinsic contributions and thereby determine the intrinsic damping. The comparison of the intrinsic damping to multiple theoretical calculations yields good qualitative and quantitative agreement in most cases. Furthermore, the values of the damping obtained in this study are in good agreement with a wide range of published experimental and theoretical values. Additionally, we find a compositional dependence of the spin mixing conductance.