Figure 3

(a) Schematic of the sample with MgO/CoFeB/Ta and coordinate system for FMR measurement and analysis. (b) Typical FMR spectra for 1.8-nm-thick CoFeB at various magnetic field angle. (c) Angular dependent H_res data for Ta/MgO/CoFeB (1.5–2.0)/Ta films. Circles and solid lines are experiment and fitting data with H_k2, respectively. The black dotted line is the example of the fitting without H_k2 for 1.5-nm-thick CoFeB. The angles θ_H = 0 and 90 degree correspond to the out-of-plane and in-plane magnetic field from the sample plane. Also, the inset shows the typical magnetization curve of 1.5-nm-thick CoFeB. (d–f) Thickness dependence of H_k^eff, H_k2 and H_k2/|H_k^eff|.