Abstract
We describe the specific features of electroconvection (EC) in the nematic liquid crystal (NLC) phase with short-range smectic C order (the seventh homologue of the p,n-alkyloxybenzoic acid, 7OBA, which is dimeric). These features are revealed below a definite temperature (T*) within this liquid crystal phase. By polarisation analysis of the azimuthal in-plane director deflection in the EC regime we suggest that this instability has a twist-type character. We indicate that the specificity of the temperature variation of the electroconductivity and the EC in 7OBA is determined by the smectic tilt angle magnitude and the dimer's compactness within the supramolecular complexes. We find that response times below T* are about two times shorter than those in classical NLCs, as an equalisation of both response and decay times, which is preferable in LC display techniques. A fourth frequency harmonic is detected for the first time in the N state.