Direct optical observation of vertical Bloch lines propagation by in-plane field pulses

Vertical Bloch line (VBL) motion in response to in-plane field pulses is studied by the methods of polarized anisotropic dark field observation (PADO) and high-speed photography in bubble garnets. The mobility of VBLs and their velocities are measured. New types of PADO pictures which are connected with the dynamic changes of VBL and domain wall structures are observed in the nonlinear region of Bloch line motion. A difference in the dynamic behavior of VBLs of different types is observed. A qualitative discussion of the origin of PADO contrast features and VBL behavior difference is proposed.>