# Bistable director alignments of nematic liquid crystals confined in frustrated substrates

## TL;DR

This study uses Monte Carlo simulations to analyze how frustrated substrate patterns induce bistable director alignments in nematic liquid crystals, revealing the effects of surface patterning and elastic properties on stability and switching behavior.

## Contribution

It demonstrates the origin of bistability in nematic liquid crystals confined by patterned surfaces through combined simulation and elastic theory analysis.

## Key findings

- Director field aligns along checkerboard diagonals.
- Energy barrier increases near the isotropic-nematic transition.
- Bistability is influenced by block size and elastic modulus.

## Abstract

We studied in-plane bistable alignments of nematic liquid crystals confined by two frustrated surfaces by means of Monte Carlo simulations of the Lebwohl-Lasher spin model. The surfaces are prepared with orientational checkerboard patterns, on which the director field is locally anchored to be planar yet orthogonal between the neighboring blocks. We found the director field in the bulk tends to be aligned along the diagonal axes of the checkerboard pattern, as reported experimentally [J.-H. Kim et al., Appl. Phys. Lett. 78, 3055 (2001)]. The energy barrier between the two stable orientations is increased, when the system is brought to the isotropic-nematic transition temperature. Based on an elastic theory, we found that the bistability is attributed to the spatial modulation of the director field near the frustrated surfaces. As the block size is increased and/or the elastic modulus is reduced, the degree of the director inhomogeneity is increased, enlarging the energy barrier. We also found that the switching rate between the stable states is decreased when the block size is comparable to the cell thickness.