Spin-wave resonance and magnetic anisotropy in FePt thin films

Ferromagnetic Resonance (FMR) measurements at room temperature and X-band microwave frequency were performed on polycrystalline FePt thin films with face-centered cubic structure. With the external field perpendicular to the film plane, the absorption fields H_n of the odd and even spin-wave resonance modes n detected for the Fe_0.44Pt_0.56(45 nm)/Si(1 0 0) and Fe_0.51Pt_0.49(105 nm)/Pt(55 nm)/MgO(1 0 0) films, were found to obey the well-known H_n×n² ratio, giving for these films the exchange stiffness constant values of 3.9×10⁻⁸ and 4.4×10^–7 erg/cm, respectively. The study of the out-of-plane angular dependence of the absorption field of the uniform FMR mode allowed the measurement of the effective magnetic anisotropy constants of 5.3×10⁶ , 6.4×10⁶ , and 6.7×10⁶ erg/cm³, related, respectively, to the [1 1 1], [1 0 0], and [1 1 0] textures present in the films.