Abstract: The temperature-dependent Gilbert damping in Co₂FeAl thin film grown on a Pb(Mg_{1 / 3}Nb_{2 / 3})O₃-30%PbTiO₃ substrate is investigated by the systematic measurement of physical property measurement system (PPMS) on a series of samples with different substrate temperatures. Varying the substrate temperatures from 350 ^°C to 500 ^°C, the B2 ordering degrees of Co₂FeAl thin films increase, which can lead the Gilbert damping to decrease, indicated by the field-sweep in-plane PPMS measurements. In addition, the measurement result of PPMS demonstrates that the Gilbert damping decreases first with measurement temperature decreasing down to about 150 K, then increases at a measurement temperature of ∼ 50 K, and decreases again with the measurement temperature decreasing. There are two independent damping manners, namely bulk damping and surface damping, which contribute to the Gilbert damping. Moreover, the observed peak of Gilbert damping at ∼ 50 K can be attributed to the spin re-orientation transition at the Co₂FeAl surface, which is similar to the result of the effective magnetization as a function of measurement temperature. The result presents the evidence for further studying the Gilbert damping in Co₂FeAl thin film.

Key words: Gilbert damping, Co₂FeAl thin film, B2 ordering degree