title: Convection-roll instability in spite of a large stabilizing torque.
abstract: Two electroconvection (EC) pattern morphologies--a cellular and a subsequent roll pattern--have been detected in the same frequency range in a nematic with positive permittivity and conductivity anisotropies. The frequency dependences of the onset voltages and critical wave numbers have been determined both for homeotropic and planar alignments. It has been proven that both pattern morphologies have a dielectric time symmetry. We also discuss possible sources for the pattern formation in the frame of both the isotropic (Felici-Benard) mechanism, as well as the standard model of EC.
authors.affiliation: Centre for Liquid Crystal Research, Professor U.R. Rao Road, P.B. No. 1329, Jalahalli, Bangalore 560 013, India.
authors.forename: Pramoda
authors.initials: P
authors.lastname: Kumar
authors.forename: Jana
authors.initials: J
authors.lastname: Heuer
authors.forename: Tibor
authors.initials: T
authors.lastname: Tóth-Katona
authors.forename: Nándor
authors.initials: N
authors.lastname: Eber
authors.forename: Agnes
authors.initials: A
authors.lastname: Buka