The mountain defect. A new kind of planar defect in surface stabilized smectic C liquid crystals

Abstract

A new kind of planar chevron defect, which we call the ‘mountain defect’ due to its mountain-shaped appearance under the microscope, is observed in chevron surface stabilized smectic C liquid crystal cells for both chiral (ferroelectric) and achiral materials. Polarized optical microscopy investigations reveal that this kind of defect, which can either appear spontaneously and grow slowly over days, weeks and months or can be induced by applying an electric field or mechanical distortion, mediates change in the chevron interface position, separating chevron domains of differing chevron interface position. The full three dimensional layer structure of this defect and its relation with other commonly seen line defects in such cells, like zig-zag walls and field lines, will be presented. The formation of this kind of defect indicates that chevron structure is not necessarily a stable structure in these cells.