Polar columnar liquid crystals

This is the authors' abstract. We don't add key points for this paper.

In this article, polar columnar liquid crystals are reviewed. After introducing conventional ferroelectric liquid crystals such as smectic C* phases, bent-core smectic polar phases and chiral discotic phases, we stress that the polarisation direction existing in the xy plane (layer plane) is a common feature. Extensive attempts to realise polar columnar structures with the polarisation along the z axis (Ising type) are reviewed. Although some of them have a long life of polar order after turning off an electric field, a genuine columnar ferroelectric liquid crystal with Ising polarisation has not been discovered until quite recently. Finally, we describe the details of the process towards the discovery, structural features, physical properties and possible applications of this novel material.