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arXiv · 1504.01297

Rotation of a liquid crystal by the Casimir torque

David A. T. Somers·Jeremy N. Munday
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Abstract

We present a calculation of the Casimir torque acting on a liquid crystal near a birefringent crystal. In this system, a liquid crystal bulk is uniformly aligned at one surface and is twisted at the other surface by a birefringent crystal, e.g. barium titanate. The liquid crystal is separated from the solid crystal by an isotropic, transparent material such as SiO$_2$. By varying the thickness of the deposited layer, we can observe the effect of retardation on the torque (which differentiates it from the close-range van der Waals torque). We find that a barium titanate slab would cause 5CB (4-cyano-4$'$-pentylbiphenyl) liquid crystal to rotate by 10$^\circ$ through its bulk when separated by 35 nm of SiO$_2$. The optical technique for measuring this twist is also outlined.

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David A. T. Somers, Jeremy N. Munday. 2015-04-06. Rotation of a liquid crystal by the Casimir torque. https://doi.org/10.1103/physreva.91.032520

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