Undulations of smectic A layers in achiral liquid crystals manifested as stripe textures

Self-assembly of organic molecules represents a fascinating playground to create various liquid crystalline (LC) nanostructures. In this work, we study layer undulations on micrometer scale in smectic A phases for achiral compounds, experimentally demonstrated as regular stripe patterns induced by thermal treatment. Undulations including their anharmonic properties are evaluated by means of polarimetric imaging and light diffraction experiments in cells with various thicknesses. The key role in stripe formation is played by high negative values of the thermal expansion coefficient.