title: Flexoelectrically driven electroclinic effect in the twist-bend nematic phase of achiral molecules with bent shapes.
abstract: We extend the twist-bend nematic (N(TB)) model to describe the electro-optics of this novel phase. We predict an electroclinic effect (ECE) subject to a dc electric field E applied perpendicular to the helix axis or wave vector q, with rotation of the N(TB) optic axis around E. This linear effect, with its flexoelectric origin, is a close analog to the electro-optic effects observed for chiral liquid crystals. However, in nematics composed of achiral molecules having a bent shape, it is the electro-optic signature of the N(TB) phase. We test our model experimentally in the low-temperature nematic phase of the odd liquid crystal dimer, CB7CB, with its molecules having, on average, a bent shape. The ECE measurements confirm the previously proposed twist-bend nematic structure of this phase, with its broken chiral symmetry, extremely short (<10  nm) doubly degenerate pitch and ultrafast, submicrosecond response times.
authors: Physique des Systèmes Complexes, Université de Picardie Jules Verne, 80039 Amiens, France.
authors: C
authors: C
authors: Meyer
authors: G R
authors: GR
authors: Luckhurst
authors: I
authors: I
authors: Dozov
mesh_terms: D050866:Liquid Crystals / Q000737:chemistry*; D008956:Models, Chemical; D013237:Stereoisomerism