Statistical distribution of the internal field in planar ferrites

The effects of nonellipsoidal geometry and the role of corners and edges of planar ferrite elements in current microwave and millimeter wave devices are investigated numerically using micromagnetic methods. The noncollinear static magnetization ground state is calculated for the case of three-dimensional rectangular Y₃Fe₅O₁₂ (YIG). The statistical distribution of the internal field over the YIG volume was obtained for different aspect ratios. The distribution of the internal field is bimodal. The low-field mode is concentrated in the volume, the high-field mode is produced by the surface of the ferrite. The nonuniform magnetization persists well in fields above 1.5 times the 4πM_s magnetization, requiring higher bias fields for proper operation of planar ferrite devices.