Evolution of spin dynamics with thickness and temperature in full Heusler alloy Co₂MnGa thin films.

The full Heusler alloy Co₂MnGa (CMG) has attracted significant attention due to its unique magnetic and non-trivial electronic properties. In this study, we investigate the temperature and thickness dependence of spin dynamics in CMG thin films using broadband ferromagnetic resonance under an out-of-plane magnetic field. The measurements were conducted over a temperature range of 135 K to 300 K on films with thicknesses of 20 nm, 60 nm, and 80 nm. Alongside the uniform mode, a perpendicular standing spin wave appeared in the spectra at lower magnetic fields. The difference in the effective magnetization obtained from both modes permits the extraction of the exchange stiffness. We observe a decrease in the exchange stiffness with increasing temperature, likely due to thermal agitation weakening exchange interactions. Furthermore, the thickest film exhibits the highest exchange stiffness. While the intrinsic damping parameter remained relatively constant ( < 1.5 x 10³ ) for the 80 nm and 60 nm films across the entire temperature range, it increased in the 20 nm film below 200 K. These results demonstrate that CMG films possess robust spin dynamic properties, making them promising candidates for high-speed and energy-efficient spintronic applications.