Effects of CoFe Alloy Composition on Magnetization Dynamics and Magnetic Thermal Transport

Abstract

The lifetime of magnetic excitations in metals is governed by scattering rates between magnons and electrons. Recent investigations [1, 2] document how magnetization dynamics vary with composition in magnetic metal alloys due to changes in their electronic band structures; e.g. Co0.25Fe0.75 thin-films display low magnetic damping (α ~ 10-4). In my talk, I will present experimental measurements of magnetic damping, ultrafast magnetization dynamics, and thermal transport properties of CoFe magnetic alloys, varying with alloy composition. To explore the magnetization dynamics, I use a time-resolved MOKE set-up to observe ultrafast demagnetization in a few hundred femtoseconds followed by precessional dynamics. Through TDTR measurements, I check if lower electron-magnon scattering rates lead to improved thermal transport. My investigation sheds light on how magnon-electron scattering rates govern dynamics on femtosecond (ultrafast demagnetization), nanosecond (magnetic precession and damping), and microsecond time-scales (thermal transport of energy). *This work was supported by the U.S. Army Research Laboratory and the U.S. Army Research Office under grant # W911NF-18-1-0364.