13:30 〜 15:30
▲ [18p-PB1-24] Temperature dependence of Gilbert damping constant in amorphous Co-Fe-B thin films
キーワード：Temperature dependence of Magnetization dynamics, Broadband ferromagnetic resonance, Amorphous Co-Fe-B thin films
Soft amorphous Co-Fe-B thin films have attracted extensive interest thanks to the low Gilbert damping constant (a), high spin polarization which are beneficial to spintronics devices such as MRAM, and the spin-based logic systems. Even though a in Co-Fe-B thin films has been widely investigated, the details about the effect of temperature on aare not understood fully. Herein we evaluate a at various temperatures of amorphous Co-Fe-B thin films with the different thicknesses by a broadband ferromagnetic resonance (FMR) measurement, and discuss the effect of temperature on a in these films.
Figs. 1 (a), (b), and (c) show the temperature dependence of the effective saturation magnetization (4pMs,eff), the inhomogeneous field (DH0), and a for Co-Fe-B thin films with the thickness of 5, 10, and 15 nm. In Fig. 1 (a), 4pMs,eff slightly increases as the temperature decreases. The thinner the film is, the smaller 4pMs,eff is obtained, which might be due to the enhancement of the surface anisotropy. On the other hand, the temperature dependence of DH0 (Fig. 1 (b)) and a (Fig. 1 (c)) for all samples look more featured, namely, as the temperature decreases, these parameters slightly increase down to 150 K and then markedly increase below 150 K, which might be similar to that of the electrical conductivity [1]. Moreover, the increment of a with temperature in 5-nm-thick film becomes larger, which might be ascribed to the magnetic inhomogeneity such as the anisotropy dispersion. These results suggest that the tendency of damping in Co-Fe-B films with temperature is mainly consistent with that expected by intra-band transition.
References: [1] JAP 50, 7726 (1979). Authors acknowledge Core Research Cluster and CIES collaborative research programs of Tohoku Univ., KAKENHI Grant No. JP17H03226, and ASRC.
Figs. 1 (a), (b), and (c) show the temperature dependence of the effective saturation magnetization (4pMs,eff), the inhomogeneous field (DH0), and a for Co-Fe-B thin films with the thickness of 5, 10, and 15 nm. In Fig. 1 (a), 4pMs,eff slightly increases as the temperature decreases. The thinner the film is, the smaller 4pMs,eff is obtained, which might be due to the enhancement of the surface anisotropy. On the other hand, the temperature dependence of DH0 (Fig. 1 (b)) and a (Fig. 1 (c)) for all samples look more featured, namely, as the temperature decreases, these parameters slightly increase down to 150 K and then markedly increase below 150 K, which might be similar to that of the electrical conductivity [1]. Moreover, the increment of a with temperature in 5-nm-thick film becomes larger, which might be ascribed to the magnetic inhomogeneity such as the anisotropy dispersion. These results suggest that the tendency of damping in Co-Fe-B films with temperature is mainly consistent with that expected by intra-band transition.
References: [1] JAP 50, 7726 (1979). Authors acknowledge Core Research Cluster and CIES collaborative research programs of Tohoku Univ., KAKENHI Grant No. JP17H03226, and ASRC.