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TT: Fachverband Tiefe Temperaturen

TT 45: Correlated Electrons: Poster Session

TT 45.68: Poster

Thursday, March 29, 2012, 15:00–19:00, Poster B

Thin film growth and characterization of the neutral-ionic phase transition system tetrathiafulvalene-p-chloranil — •Achim Rippert, Milan Rudloff, Kai Ackermann, and Michael Huth — Physikalisches Institut, Goethe-Universität, Max-von-Laue-Str. 1, 60438 Frankfurt am Main

Tetrathiafulvalene-p-chloranil (TTF-QCl4) thin films have been prepared by physical vapor deposition of the pre-reacted source material on different substrate materials. We studied the growth characteristics and electronic transport properties with a view to the influence of substrate-induced effects, such as clamping and strain, on the electronic properties of the layers. TTF-QCl4 is a mixed-stack organic charge transfer compound that shows a temperature-driven paraelectric-to-ferroelectric phase transition associated with a charge of the charge transfer degree at 81 K. This phase transition brings about a distinct change of the electrical conductivity, an anomaly of the frequency dependent dielectric function, as well as a color change of the material. Via partial Br-Cl-substitution the phase transition can be shifted to 0 K resulting in a quantum critical state. Our research aims for taking advantage of thin-film specific control mechanisms, such as induced biaxial strain and electrostatic field effects, and thus providing a new perspective on the neutral-ionic phase transition in the one-dimensional, mixed-stack organic charge transfer compounds.