Perpendicular Anisotropy and g-Factor of Sputtered Ni Films on Si(111) Studied by Angle-Dependent Ferromagnetic Resonance

Abstract

Ni films with thicknesses of 312 and 1011\,Å were grown on Si(111) by dc magnetron sputtering at room temperature and studied by atomic force microscopy, grazing-incidence X-ray diffraction, X-ray reflectivity, magnetometry and angle-dependent ferromagnetic resonance. Both films are polycrystalline fcc Ni with smooth surfaces, a bulk-like (111) lattice spacing and a saturation magnetization of ${\approx}480$\,emu\,cm$^{-3}$, and both are magnetized in plane. The angular dependence of the resonance field, from the film plane to the film normal, is described by a uniaxial anisotropy model with first- and second-order terms. From this model, $g = 2.160\pm0.005$ and $2.101\pm0.014$ and effective perpendicular anisotropies of $(6.0\pm0.4)\times10^{5}$ and $(4.5\pm0.6)\times10^{5}$\,erg\,cm$^{-3}$ were obtained for the thinner and thicker film, respectively. The conventional analysis of only the in-plane and perpendicular resonances gives $g$-factors that are lower by 0.02--0.04. The perpendicular linewidths give upper limits for the Gilbert damping of $α\le 0.030$ and $\le 0.038$.