Structure of the cholesteric-isotropic interface

The interface of a cholesteric liquid crystal with an isotropic fluid can display a range of unusual properties, such as a layer of topological defects close to an undulated interface. These properties have been known for a long time and have been explored for technological applications as a tunable substrate for colloidal self-assembly. However, from a fundamental point of view, the cholesteric-isotropic interface remains poorly understood and even basic properties, such as the dependence of the surface tension on the attributes of the liquid crystal, remain unknown. Here, we present a systematic calculation of the structure and surface tension of the cholesteric-isotropic interface and how these vary with the properties of the liquid crystal. We find that the anchoring at the interface depends on the pitch of the cholesteric and the interface undulations scale with the square root of the pitch. Our results also suggest the intriguing possibility of wetting of this interface by a blue phase.