An improvement of distributed Bloch line model for low-q bubble materials

A way of improving the intrinsic accuracy of the distributed Bloch line model is proposed for use in practical simulations of vertical Bloch lines in small-diameter bubble materials with relatively small q value. The model is based on approximate equations of wall motion derived from the Gilbert equation. As the q value is decreased, the inexact nature of the equations of wall motion gives rise to an unbalanced residual component in the effective reversible force. The residual component is found to concentrate around a Bloch line and causes the calculated domain motion to be quite unreliable. It is also found that the density of the residual force is proportional to the inverse square of the average radius of curvature of the domain wall in the neighborhood of a Bloch line. A simple expression is derived for a correction force density which cancels the residual force. The derivation of the correction force density is presented together with numerical results showing the effectiveness of the correction