Han Bao-Shan

Break-Down of Vertical-Bloch-Line Chains in Ordinary Hard Bubble Walls Subjected to an In-plane Field

An experimental and theoretical study was carried out on the break-down of vertical-Bloch-line (VBL) chains in ordinary hard bubble walls subjected to an in-plane field, Hip. Other than a single critical value, a critical range of in-plane field, from Hip(1) to Hip(2), was found. When Hip < Hip(1) the VBL chains keep unchanged; whereas when Hip(1) < Hip < Hip(2), more and more hard domains are softened. Above Hip(2) all VBL chains are broken-down. A theoretical analysis showed that the critical range of Hip is originated from the serpentine curving of domain walls, and a relation Hip(2)/Hip(1)=√2, was obtained, which is in good agreement with the experiments.

Influence of in-plane field on the stability of vertical Bloch line chains in hard domains of Garnet bubble films

The stability of vertical Bloch line (VBL) chains was statistically studied for all three types of hard domains in garnet bubble films subjected to an in-plane field Hip. With a set of integrate data taken from seven bubble samples and with two typical figures of a sample, four main features of the behavior of VBL chains subjected to Hip were summarized.

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.

DEPENDENCE OF DOMAIN STRUCTURES ON Au THICKNESS IN Co/Au MULTILAYER FILMS

The magnetic force images and surface topography images of sputtered Co/Au multilayer films in remnant state were measured by magnetic force microscopy. From the surface magnetic structures shown in the magnetic force images it can be seen that the domain pattern and size vary with the increase of the thickness t of the non-ferromagnetic Au layer remarkably. With the measurements of the effective perpendicular anisotropy Ku and the domain period d, it was found that there are similar trends of d and Ku as functions of t. The variations of the domain pattern and size were qualitatively interpreted in terms of magnetic domain theory. the theoretical relations of d and the domain wall energy σw vs t were calculated. As t = 8.5 AL(1AL=0.235 nm), the largest σw is 11 mJ/m2.

Formation of multi-branched domains in garnet bubble films by low-bias-pulse method

The formation of multi-branched domains (MBDs) at low static bias field was first studied. With multiple branches, MBDs contain more or less same-signed vertical-Bloch-lines (VBLs) in their walls. Experiments on four samples have shown that under certain conditions, the amount and hardness of the MBDs formed can be easily controlled, and so-called low-bias-field method is another effective way to form VBL chains. It was found that MBDs are formed due to the expansion of domain segments after compressed by a rectangular bias pulse. The number of VBLs nucleated in domain walls is affected by the space where the domains expand rapidly.