Separation of the two-magnon scattering contribution to damping for the determination of the spin mixing conductance

TL;DR

This study develops a model to separate two-magnon scattering effects from other damping contributions in epitaxial Fe layers, enabling more accurate measurement of spin mixing conductance by accounting for defect density influences.

Contribution

The paper introduces a method to isolate two-magnon scattering in damping measurements, improving the accuracy of spin mixing conductance determination in epitaxial magnetic films.

Findings

Separation of two-magnon scattering from other damping effects.

More accurate measurement of spin mixing conductance.

Reduced influence of defect density variability.

Abstract

We present angle dependent measurements of the damping properties of epitaxial Fe layers with MgO, Al and Pt capping layers. Based on the preferential distribution of lattice defects following the crystal symmetry, we make use of a model of the defect density to separate the contribution of two-magnon scattering to the damping from the isotropic contribution originating in the spin pumping effect, the viscous Gilbert damping and the magnetic proximity effect. The separation of the two-magnon contribution, which depends strongly on the defect density, allows for the measurement of a value of the effective spin mixing conductance which is closer to the value exclusively due to spin pumping. The influence of the defect density for bilayers systems due to the different capping layers and to the unavoidable spread in defect density from sample to sample is thus removed. This shows the potential of studying spin pumping phenomena in fully ordered systems in which this separation is possible, contrary to polycrystalline or amorphous metallic thin films.