Investigations of lines in domain walls of yttrium orthoferrite

We report on the visualization of domain walls (DWs) by means of the Faraday effect for the case when the direction of light has a nonzero projection on the easy axis. Observations of individual DWs between crossed polarizers reveal segments of different brightness. Under the influence of an external magnetic field, the boundaries between these segments move along the DWs. The positions of the boundaries coincide with those observed by a dark field method and indicate locations of lines of zero magnetization. Evidence is provided that the DW contrast, that depends on the polarization of the incident light, is associated with the DW inclination and crystallographic birefringence. (C) 2002 American Institute of Physics.