Critical curves have been calculated for the graphical determination of the magnetization direction as function of applied magnetic field in ion-implanted garnet films having cubic anisotropy. Up to three stable magnetization directions may exist when the applied field is inside the critical curves. This leads to the formation of charged walls. The hard magnetization directions are found to be favorable directions for charged walls and the easy magnetization directions are unfavorable. The complex domain-wall patterns revealed by Ferrofluid techniques in 1-μm magnetic bubble devices are explained by using the calculated critical curve. Futhermore, critical curves for several different symmetries have also calculated to correspond to different crystallographic orientations and garnet material parameters.