The Gilbert damping of thickness-dependent epitaxial single-crystal Heusler Co2FeAl films at various temperatures

Gilbert damping in epitaxial Heusler Co2FeAl films with thickness varying from 3 nm to 9 nm are investigated by broadband ferromagnetic resonance (FMR) with a temperature range of 5 K to 300 K. Gilbert damping shows a continuous decrease with the increasing thickness of Co2FeAl films. Moreover, an enhanced peak of the Gilbert damping is observed with increasing temperature up to approximately 50 K for 3 nm,6 nm and 9 nm−thick Co2FeAl films, which may be attributed to the spin reorientation transition at Co2FeAl /MgO interface. Further, we analyzed the linewidth with a superposition of a uniaxial and a fourfold anisotropy for all samples, which suggests that FMR linewidth in epitaxial Co2FeAl films stems from two-magnon scattering. The change of Gilbert damping is confirmed to originate from various order degrees of the B2 phase with the growth of CFA film, impacting the control of magnetic damping in spin-based nanodevices.