High-Frequency Susceptibility of the Ferromagnetic Resonance in Thin Films with Random One- and Two-Dimensional Inhomogeneities in the Magnetic Anisotropy

The effect of random one- (1D) and two-dimensional (2D) inhomogeneities of the magnetic anisotropy on the shape and width of ferromagnetic resonance line in a thin film has been studied in the standard and new self-consistent approximations. It has been shown that resonance peaks in the case of 2D inhomogeneities are much narrower than those for 1D ones. Peaks are asymmetric in both the 1D and 2D cases, but asymmetry is larger in the latter case. As the correlation wavenumber of inhomogeneities kc increases, the width of a resonance line decreases and its amplitude increases. The amplitude of the FMR peak for 2D inhomogeneities increases much faster than that for 1D inhomogeneities. At the critical dimensionless parameter kcd/π ~ 1, where d is the thickness of the film, the width of the resonance line has an inflection point and the asymmetry of this line and the shift of the ferromagnetic resonance peak are maximal. It has been shown that the new self-consistent approximation reproduces the shape of the resonance line much better than the standard self-consistent approximation.