Periodic lattices of frustrated focal conic defect domains in smectic liquid crystal films

We have created periodic lattices of close-packed non-toroidal focal conic domains (FCD) in smectic A liquid crystal films deposited on solid substrates that induce unidirectional planar anchoring, at the interface with air which induces homeotropic anchoring. Each cell of the quasi-hexagonal lattice contained a FCD with an eccentric ellipse aligned with the planar anchoring direction and tilted from the solid substrate towards the free interface. In contrast to common toroidal FCDs, the ellipse was truncated by both the substrate and the free interface, and its longest portions were virtual. Such geometry results from a complex balance between the distortion of the smectic layers, anchoring and surface tension achieved through multiple frustrations of the smectic layered structure and anchoring at the interfaces, and creation of additional defects at the boundaries between neighbouring FCDs in the lattice. © 2012 The Royal Society of Chemistry.