Linewidth of ferromagnetic resonance in holmium yttrium garnet ferrites

The specific features experimentally observed in the behavior of the linewidth of ferromagnetic resonance in holmium yttrium garnet ferrites were investigated as a function of the orientation of the external magnetic field at low temperatures. The analysis was performed using the model spectrum of holmium ions, according to which the ground state of these ions is represented by two closely spaced levels (quasi-doublet) that are sufficiently far removed from the other levels. A comparison of the theoretical results with the experimental data was carried out.