Three-dimensional dynamics of solitary vertical Bloch lines in domain walls of garnets

The results of a simulation of vertical Bloch lines (VBL) dynamics in garnet films are presented using the three-dimensional Landau-Lifshitz equation. The behavior of VBLs depends especially on the magnetic field driving the domain wall. At small driving fields the motion of VBL under the influence of a gyroscopic force is similar to the one obtained with the help of the one-dimensional Slonczewski equations. At large driving magnetic fields horizontal Bloch lines (HBLs) are generated in the domain wall. This fact leads to decay of a vertical N pi-Bloch line into a packet of N separated pi-lines. The motion of the horizontal Bloch line provides an annihilation of the leading pi-VBL and the simultaneous generation of a pi-line behind the packet. The velocity of the packet as a whole is lower than that of the one-dimensional N pi-VBL. The results of the simulation of VBL dynamics using the three-dimensional Landau-Lifshitz equations and two-dimensional Slonczewski equations look very similar. Based on this Fact the head-on collisions of two packets of 2 pi and -2 pi VBLs were investigated with the help of two-dimensional Slonczewski equations. After collisions of two +/-2 pi VBLs, two with charge +/-pi move in the initial directions in some interval of the driving magnetic field. The partial restoration of the packets of +/-2 pi takes place. Outside this interval the full annihilation of the colliding packets +/-2 pi-VBLs takes place. (C) 1998 Elsevier Science B.V. All rights reserved.