Computer simulation of magnetic domain wall motion to derive effective interaction forces between vertical Bloch lines

Magnetization configurations of a planar domain wall containing vertical Bloch lines (VBL's) were calculated using equations of wall motion which were extended to include wall-demagnetizing field originating from the magnetic charges around the VBL's. The wall was given initial configuration defined appropriately and left to be relaxed under an inplane field applied tangentially until the VBL's almost ceased to move. Because of the introduction of the magnetostatic interaction the VBL's were observed to attract each other to make a cluster. The derivation of the magnetostatic force terms in the equations of wall motion, methods of numerical calculation, and results obtained for two to four clustered VBL's are given.