Pereira Maria S S, Lyra Marcelo L, de Oliveira Italo N
Instituto de Física, Universidade Federal de Alagoas 57072-970 Maceió-AL, Brazil.
Phys Rev Lett. 2009 Oct 23;103(17):177801. doi: 10.1103/PhysRevLett.103.177801. Epub 2009 Oct 20.
Strongly anchored free-standing smectic films usually present a stepwise reduction of the number of layers when the temperature is raised above the smectic-isotropic bulk transition temperature. Here, we demonstrate that a field-induced layer thinning transition can take place in smectic films with a negative dielectric anisotropy even below the bulk transition temperature. Using an extended McMillan's model, we provide the phase diagram of this layering transition and show that, when the field is raised above the bulk transition field, the film thickness reduction is well described by a power law with an exponent that depends on the temperature and the aspect ratio of the liquid-crystal molecule.
当温度升高到近晶-各向同性体相转变温度以上时，强锚定的独立近晶膜通常会呈现出层数的逐步减少。在此，我们证明，即使在体相转变温度以下，具有负介电各向异性的近晶膜中也会发生场致层变薄转变。使用扩展的麦克米兰模型，我们给出了这种分层转变的相图，并表明，当场强升高到体相转变场以上时，膜厚度的减小可以用幂律很好地描述，其指数取决于温度和液晶分子的纵横比。
