Magnetic anisotropy of epitaxial MgO∕Fe∕MgO films studied by network analyzer ferromagnetic resonance

The dynamic magnetic properties of MgO∕Fe epitaxial thin films are investigated through a network analyzer ferromagnetic resonance in the 0–26-GHz range. The high-frequency response is measured for applied in-plane magnetic fields comparable to the fourfold magnetocrystalline anisotropy of the film, resulting in large-angle in-plane quasistatic motion of the magnetization. We show that the variation of the resonance frequency with both the amplitude and the direction of the external field is in good agreement with the ferromagnetic resonance equations, allowing precise determination of the anisotropy.