Stripe instabilities in the menisci of free-standing smectic films: influence of the phase sequence of the mesogenic material

ABSTRACT

We briefly report experimental observations of striped patterns in the menisci of free-standing smectic C films. The results were obtained with a mesogenic compound that transits directly from the nematic phase to the smectic C phase, without an intermediate smectic A phase. In this case, it is shown that stripes do not correspond to undulations of the smectic free surface and smectic layers, as was indeed evidenced in previous studies with other compounds and different phase sequences. Hence, our results show that the nature of striped patterns in free-standing films depends on the phase sequence of the considered materials. Further experimental and theoretical works are still required to fully elucidate the physical mechanisms that drive the onset of patterns in such systems.

GRAPHICAL ABSTRACT

KEYWORDS:

• Smectic free-standing films
• pattern formation
• optical microscopy
• phase shifting interferometry

Acknowledgments

The authors would like to thank N.A. Clark for kindly sending us a few milligrams of the compound we used in our experiments (see Figure 1(a)).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

We acknowledge financial support from a joint research fellowship between the EU and the University of Tunis El Manar (Erasmus Mundus EU-METALLIC II Cardiff Metropolitan University). We thank the instrumentation team and the mechanics shop of the laboratory for their valuable help and continuous technical assistance.