Growth and magnetic characterization of epitaxial Fe ₈₁Ga ₁₉/MgO (100) thin films

Using magnetization and ferromagnetic resonance techniques, we have characterized Fe81 Ga19 (100) thin films (90 nm thick) grown on MgO (100). We have observed that for low sputtering powers (<35 W) it is possible to grow films with cubic magnetic symmetry, and that larger powers induce an in-plane magnetic easy axis. Films with cubic symmetry were further characterized using ferromagnetic resonance at frequencies of 34 and 9.7 GHz. From the angular variation of the resonance field we have obtained the cubic magnetocrystalline anisotropy constant, K1 =2× 105 erg cm3, and the saturation magnetization, M∼1460 G. The magnitude and the angular variation of the linewidth suggest an important contribution of the two-magnon scattering mechanism to the relaxation of the magnetic excitations.