Stripe instabilities in menisci of free-standing smectic films with a direct transition from smectic C to an isotropic or nematic phase

摘要

Regular periodic stripe patterns that are found in the menisci of smectic C and C freely suspended films were described first by Meyer and Pershan (Solid State Commun. 13 (1973)) more than 40 years ago, but their physical origin is still under debate. Loudet et al. (Phys. Rev. Lett. 106 117, 802 (2011)) proposed a layer dilatation model to explain their formation. Our observation of such patterns in films with a direct transition from smectic C to a nematic or isotropic phase is in sharp conflict with that model. Moreover, we demonstrate the disappearance of the patterns at the transition from synclinic to anticlinic smectic C phases. An essentially different explanation of the physical mechanism of the stripe formation must be sought. We propose potential sources of the instability.