Formation of Multi-branched Domains in Magnetic Garnet Bubble Films

A “low-bias-field method” for the formation of multi-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” Hd, the patterns of MBD’s become more and more complex, accompanying with the successive formation of three types of hard domains. The typical photos and the static properties of MBD’s are presented.