Dynamic Bloch-line stacking—A new domain-wall structure at high drives

The equations of motions of a flat twisted domain wall are solved numerically and the structure of the wall is investigated during motion in high-drive fields. A new domain-wall structure is obtained—dynamic Bloch-line stacking—i.e., Bloch lines are seen to nucleate faster than the ones generated earlier can punch through and so stack at both film surfaces. Thus in the moving wall more than one Bloch line is present at the same time. When dynamic Bloch-line stacking occurs in a material with high damping the velocity of the wall becomes only a weak funciton of the drive. Some supporting experimental data is discussed. In a low-damping material dynamic Bloch-line stacking is found to occur also at sufficiently high drives, but published corroborating experimental data seems to be lacking.