Charge Ordering Induces a Smectic Phase in Oblate Ionic Liquid Crystals

We report a computer simulation study of an electroneutral mixture of oppositely charged oblate ellipsoids of revolution with aspect ratio A = 1/3. In contrast with hard or soft repulsive ellipsoids, which are purely nematic, this system exhibits a smectic-A phase in which charges of equal sign are counter-intuitively packed in layers perpendicular to the nematic director.