Formation of multi-branched domains in magnetic garnet bubble films

A "low-bias-field method" for the formation of mult-branched domains (MBD's) in garnet bubble films has been introduced. By using this method, only a single MBD can be formed each time inside a pancake coil with an inner diameter of 1 mm. The formation of MBD's is associated with the nucleation of vertical-Bloch-lines in their walls. Therefore, with the decrease of the bias field H-b from the "critical static bias field for multi-branched expansion" II[d], the patterns of MBD's become more and more complex, accompanying with the successive formation three types of hard domains. The typical photos and the static properties of MBD's are presented.