Field-induced layer thinning transition on free-standing smectic films

TL;DR

This paper demonstrates a field-induced layer thinning transition in free-standing smectic films with negative dielectric anisotropy, occurring below the bulk transition temperature, and provides a phase diagram using an extended model.

Contribution

It introduces a new field-induced layering transition in smectic films below the bulk transition temperature, expanding understanding of phase behavior under external fields.

Findings

Layer thinning transition occurs below bulk transition temperature.

The transition follows a power-law with a temperature and aspect ratio-dependent exponent.

Phase diagram of the transition is provided using an extended McMillan's model.

Abstract

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.