title: Temporal evolution and alternation of mechanisms of electric-field-induced patterns at ultralow-frequency driving.
abstract: The temporal evolution of patterns within the driving period of the ac voltage was studied in the 10-mHz-250-Hz frequency range. It was shown that the stationary electroconvection pattern of the conductive regime transforms into a flashing one at ultralow frequencies, existing only in narrow time windows within the period. Furthermore a transition between electroconvection and flexoelectric domains was detected which is repeating in each half period. The two patterns are well separated in time and in Fourier space. Simultaneous current measurements uncovered that the electric properties of the polyimide orienting layers influence the redistribution of the applied voltage. The experimental findings are in good qualitative agreement with the theoretical predictions based on an extended standard model including flexoelectricity.
authors.affiliation: Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, H-1525 Budapest POB 49, Hungary.
authors.forename: Nándor
authors.initials: N
authors.lastname: Éber
authors.forename: Laura O
authors.initials: LO
authors.lastname: Palomares
authors.forename: Péter
authors.initials: P
authors.lastname: Salamon
authors.forename: Alexei
authors.initials: A
authors.lastname: Krekhov
authors.forename: Ágnes
authors.initials: Á
authors.lastname: Buka