Motion and interaction of dislocations in electrohydrodynamic convection of nematic liquid crystals

Two typical motions of dislocations, climb and glide, and their mutual interactions are studied experimentally in a layered pattern of electrohydrodynamical convective rolls of nematic liquid crystals under well controlled initial conditions. It was found that two kinds of forces acted on the dislocations with opposite Burgers vectors. The first kind is a pattern-selection force under which the dislocation moves at constant velocity. The second kind is an attractive interaction force. When dislocations are approaching each other, the effective length of the latter is of short range, typically of the order of the wavelength of the pattern.