Stripe-to-bubble transition of the second kind of dumbbell domains subjected to both static bias field and in-plane field

Abstract

Stripe-to-bubble transition (SBT) of the domains that are transformed from the second kind of dumbbell domains (IIDs), which are subjected to an in-plane field H ip in a fixed static bias field H b, was studied experimentally. The results suggest that H b plays an important role in SBT. There are four characteristic static bias fields from low to high, ( H b) h, ( H b) I, ( H b) II and ( H b) c. When H b<( H b) h, a high H ip has to be applied so that SBT can take place. The H ip increases as H b decreases. In fact, in this case, before SBT takes place, all of the IIDs lose all their vertical Bloch lines (VBLs), and transform to soft domains. When H b is higher than ( H b) h and ( H b) I, the ordinary hard bubbles (OHBs) and the first kind of dumbbell domains (IDs) begin to appear in the domains transformed from IIDs, after SBT takes place. When H b>( H b) II, some of the IIDs collapse in stripe shape, at a low H ip, instead of SBT. The percentage of IIDs that collapse in stripe shape increases rapidly as H b increases. It increases to 100% when H b=( H b) c. It is suggested that, in this case, all VBLs in IIDs walls break down at the same time instead of losing gradually. This phenomenon may act as a clue to the further research of the mechanism of the VBLs breaking down when subjected to both H b and H ip.