Effects of CoFe Alloy Composition on Non-Electronic Thermal Transport*

CoFe magnetic alloys feature interesting magnetization dynamics that vary as a function of composition. This is, likely, due to their unique electronic band structures that allow for a suppression in electron-magnon scattering at certain CoFe compositions. Recent investigations have shown that Co_0.25Fe_0.75 has low damping (α ~ 10^-4), comparable to ferrimagnetic insulators. In this talk, I investigate the effect of composition on thermal transport. Using time–domain thermo-reflectance (TDTR) analyses, I present a high-resolution thermal conductivity map of a bulk CoFe diffusion multiple. This map allows us to correlate the alloy composition to thermal conductivity. I also report on thermal conductivity and electrical resistivities of sputtered thin-films. To estimate the non-electronic thermal conductivity, we use the Wiedemann-Franz law to subtract the electronic contribution. We observe a correlation between the composition, magnetic damping parameter α, and the non-electronic thermal conductivity. My investigation provides insights into electron-magnon interactions and thermal transport in magnetic metals.