Bloch lines generation in moving stripe heads

Abstract

The generation of vertical Bloch lines (VBL’s) at the head of a moving stripe domain with and without an in-plane field was studied. For an as-grown sample, the velocity saturation is independent of in-plane field direction and the same velocity as an implanted sample when the in-plane field direction is the same as the stray field in the implanted layer. When the in-plane field direction was reversed, the wall saturation velocity is higher. Overshoot starts when the wall velocity approaches the saturation velocity and increases with drive field as the stripe head becomes asymmetrically distorted. Eventually, the stripe will move at an angle. The presence and motion of VBL’s was inferred from the shape of the stripe head during and at the end of the applied pulse field, the bending of the stripe, and the presence of overshoot. In the ion-implanted film, after the generation of a pair of VBL’s on the stripe head, the positive (negative) VBL was pushed into the straight part of the stripe when the in-plane field direction is opposite (parallel) to the stray field direction in the implanted layer at the stripe head. In the as-grown film, which kind of VBL is pushed away seems random and independent of the in-plane field direction and amplitude.