Tunable magnetization relaxation of Fe_{2}Cr_{1-x}Co_{x}Si half-metallic Heusler alloys by band structure engineering

TL;DR

This study demonstrates how band structure engineering via Co doping in Fe₂Cr₁₋ₓCoₓSi Heusler alloys can significantly reduce magnetization relaxation, achieving ultra-low damping constants suitable for spintronics applications.

Contribution

It introduces a method to tune magnetic damping in Heusler alloys through Co doping, with experimental and theoretical validation showing unprecedented low damping values.

Findings

Intrinsic damping constants as low as 0.0008 achieved.

Co doping reduces extrinsic damping contributions.

Damping tuning effective at room temperature.

Abstract

We report a systematic investigation on the magnetization relaxation properties of iron-based half-metallic Heusler alloy Fe$_{2}$Cr$_{1-x}$Co_${x}$Si (FCCS) thin films using broadband angular-resolved ferromagnetic resonance. Band structure engineering through Co doping (x) demonstrated by first-principles calculations is shown to tune the intrinsic magnetic damping over an order of magnitude, namely 0.01-0.0008. Notably, the intrinsic damping constants for samples with high Co concentration are among the lowest reported for Heusler alloys and even comparable to magnetic insulator yttrium iron garnet. Furthermore, a significant reduction of both isotropic and anisotropic contributions of extrinsic damping of the FCCS alloys was found in the FCCS films with x=0.5-0.75, which is of particular importance for applications. These results demonstrate a practical recipe to tailor functional magnetization for Heusler alloy-based spintronics at room temperature