Labyrinthine instability in freely-suspended smectic films

• Applicant: Professor Dr. Alexey Eremin
• Subject Area: Theoretical Condensed Matter Physics
• Term: from 2005 to 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 14228891

Interactions between external magnetic field and the magnetization of a fluid can give rise to ferrohydrodynamic instabilities. Such instabilities, yielding fingering and maze patterns, are very common in magnetic ferrofluids and express not only a direct influence of the magnetic field on fluids but also feed back that drastically modifies the flow field. Similar phenomena can also be expected in electrically polarizable fluids or, especially, in ferroelectric liquid crystals. However, such phenomena have never been observed in liquid crystals before. In our studies, we have discovered a labyrinthine instability in freely-suspended polar smectic films. Due to the residual macroscopic polarization of the films this instability occurs spontaneously without externally applied electric field. The ultimate goal of the proposal is to study the labyrinthine growth in the smectic films and to understand the underlying instability mechanisms. A comprehensive study of the film structure an instability behavior in electric fields will be done using various experimental techniques such as microscopy, AFM, linear electro-optics and SHG. A following theoretical analysis, based on the proposed experimental studies, is aimed to elucidate the underlying role of the ferroelectric order and the mesophase structures in the instability mechanism. The outcome of this research project may significantly contribute not only into the pattern formation in liquid crystals but also in our general understanding of ferrohydrodynamic instabilities.

• DFG Programme: Research Grants
• Participating Person: Professor Dr. Ralf Stannarius