Simulation of Bloch wall motion in bubble films

Abstract

For straight Bloch walls in uniaxial bubble films, the dependence of the peak velocity and of the saturation velocity on the film thickness is given as v \propto l/h according to Slonczewski's HBL (horizontal Bloch line) model. This dependence could not be verified experimentally. For thick films the saturation velocity seems to increase again with increasing film thickness. Here the results of a direct numerical solution of the equations of motion are presented and compared with the HBL model and experimental results. The saturation velocity resulting from this simulation shows a dependence on the drive field even in case of low loss materials. This dependence increases with increasing film thickness and might explain the experimental results. Comparing the lowest value of the saturation velocity for drive fields slightly larger than necessary for punch-through with the saturation velocity predicted by the HBL model, very good agreement is found. The peak velocity is seen to decrease with increasing film thickness, but seems to tend to a finite value considerably larger than 0.