title: Electric field induced order reconstruction in a nematic cell.
abstract: We have experimentally observed the biaxial switching between two topologically distinct textures of a nematic liquid crystal cell submitted to a strong electric field. The effect is deduced from optical and electrical measurements across the cell. Above a static threshold, a bulk order reconstruction is observed, where the final nematic orientation in the centre becomes perpendicular to its initial one, inducing a total pi change of orientation across the cell. Using short electric field pulses, a higher dynamical threshold is observed. These experiments are explained by a Landau-de Gennes-Khalatnikov model. The threshold implies the local exchange of two eigenvalues of the nematic order tensor through intermediate biaxial states. The onset of the effect in a thin splay-bend wall decreases the static threshold by almost an order of magnitude. The model explains reasonably well the static and dynamic measurements within the present description of nematic biaxiality.
authors.affiliation: Dipartimento di Fisica, Istituto Nazionale di Fisica della Materia, Universitá di Calabria, Rende, 87036, Cosenza, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Barberi
authors.forename: F
authors.initials: F
authors.lastname: Ciuchi
authors.forename: G E
authors.initials: GE
authors.lastname: Durand
authors.forename: M
authors.initials: M
authors.lastname: Iovane
authors.forename: D
authors.initials: D
authors.lastname: Sikharulidze
authors.forename: A M
authors.initials: AM
authors.lastname: Sonnet
authors.forename: E G
authors.initials: EG
authors.lastname: Virga
mesh_terms: D004560:Electricity; D004563:Electrochemistry; D004574:Electromagnetic Fields; D008962:Models, Theoretical; D011108:Polymers / Q000737:chemistry; D013696:Temperature; D013997:Time Factors
chemical_list: D011108:Polymers; C422409:liquid crystal polymer