Self-collapse of Dumbbell Domains in Garnet Bubble Films

The self-collapse phenomenon of dumbbell domains was studied experimentally. The coincidence of the bias field region of self-collapse with that of collapse for both the first and second kinds of dumbbells manifests that two necessary conditions for self-collapse are: (1) sufficiently high number of vertical Bloch lines (VBLs) in their walls and (2) these VBLs are in high compression, and there exists the similarity between self-collapse and collapse in mechanism.