Investigation of the width of the FMR line in iron garnets depending on the magnitude and direction of a static magnetic field

Using an iron garnet film as an example, we performed an experimental and theoretical investigation of angular dependences of the width of the ferromagnetic resonance (FMR) line upon the variation of the magnitude and direction of a static magnetic field near its resonance value. The smallest linewidth was shown to be realized only under the condition of a simultaneous change in both the magnitude and the direction of the magnetic field with respect to the anisotropy axes. An experimental method is suggested for obtaining two-dimensional FMR spectra, which permits one to analyze the dependence of the FMR linewidth in anisotropic magnets on two parameters-the magnitude and the direction of the magnetic field. It is shown that the two-dimensional representation of FMR spectra, unlike the one-dimensional angular dependences of resonance parameters, contains more information on spectral characteristics of the film, including noncollinear field configurations. The results obtained permit one to suggest a new method of controlling FMR parameters in anisotropic magnets, which consists of changing the orientation of an additional scanning (sweeping) magnetic field with respect to the direction of the static (resonance) field. In particular, the control of the FMR linewidth may be used in designing new devices of microwave electronics.