Dynamics of magnetic domain wall and bloch line motion using 3D simulations

The dynamics of a magnetic domain wall containing vertical Bloch lines (VBL) has been numerically investigated. The wall is the kind found in thin film materials with a large anisotropy perpendicular to the plane of the film. The VBL's are all of the same chirality and are periodically repeated along the wall. The wall is driven by an applied field perpendicular to the film plane and the VBL’s are gyrotropically driven by wall motion. This simulation was performed for a wide range of applied fields. At all fields, both the wall and the VBLs distort from their equilibrium shape and finally attain a constant velicity. As show below, neither the wall velocity or the VBL velocity is a linear function of the respective drive so that the ratio of VBL velocity to wall velocity decreases, presumably, because of the observed distortion. For an applied field extrapolated to zero, the ratio agrees with the value predicted by the analytical rigid wall model. We will show the dynamic distortion by observing contours of the magnetization in-plane angle for various applied fields, the wall velocity as a function of field, the VBL velocity as a function of wall velocity and the various energies of the moving wall as a function of field.