Influence of rotating in-plane field on vertical Bloch lines in the walls of second kind of dumbbell domains

Influence of rotating in-plane field on vertical Bloch lines in the walls of second kind of dumbbell domains (IIDs) was investigated, and a critical in-plane field range [H-ip(1),H-ip(2)] of which vertical-Bloch lines (VBLs) annihilated in IIDs is found under rotating in-plane field (H-ip(1) is the maximal critical in-plane-field of which hard domains remain stable, H-ip(2) is the minimal critical in-plane-field of which all of the hard domains convert to soft bubbles (SBs, without VBLs)). It shows that the in-plane field range [H-ip(1), H-ip(2)] changes with the change of the rotating angle Deltapsi. H-ip(1) maintains stable, while H-ip(2) decreases with the decreasing of rotating angle Deltapsi. Comparing it with the spontaneous shrinking experiment of IIDs under both bias field and in-plane field, we presume that under the application of in-plane field there exists a direction along which the VBLs in the domain walls annihilate most easily, and it is in the direction that domain walls are perpendicular to the in-plane field. (C) 2004 Elsevier B.V. All rights reserved.