Structure Constant and Grain Size Determination by Ferromagnetic Resonance in Thin Magnetic Films

The paper shows that the structure constant and the average crystal grain size of anisotropic nanocrystalline magnetic film can be determined by analyzing the shape of the microwave absorption peak in sweeping the external magnetic field along the hard magnetization axis. In the theory of magnetization ripple, the surface energy density of the local magnetic anisotropy is connected with the structure constant, which can be used to determine the quality of nanocrystalline films. The effectiveness of the structure constant measurements is demonstrated on a 300-nm-thick nanocrystalline Co–P film. Spectral data on the microwave absorption are collected in the ~1 mm2 region of the film using a scanning ferromagnetic resonance spectrometer. The structure constant obtained from the spectral analysis allows detecting the average grain size of the magnetic film, which is in good agreement with transmission electron microscopy observations.