Evolution of ferroelectricity in tetrathiafulvalene-p-chloranil as a function of pressure and temperature

Armin Dengl; Rebecca Beyer; Tobias Peterseim; Tomislav Ivek; Gabriele Untereiner; Martin Dressel

doi:10.1063/1.4884964

Evolution of ferroelectricity in tetrathiafulvalene-p-chloranil as a function of pressure and temperature

J Chem Phys. 2014 Jun 28;140(24):244511. doi: 10.1063/1.4884964.

Authors

Armin Dengl¹, Rebecca Beyer¹, Tobias Peterseim¹, Tomislav Ivek¹, Gabriele Untereiner¹, Martin Dressel¹

Affiliation

¹ 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany.

PMID: 24985658
DOI: 10.1063/1.4884964

Abstract

The neutral-to-ionic phase transition in the mixed-stack charge-transfer complex tetrathiafulvalene-p-chloranil (TTF-CA) has been studied by pressure-dependent infrared spectroscopy up to p = 11 kbar and down to low temperatures, T = 10 K. By tracking the C=O antisymmetric stretching mode of CA molecules, we accurately determine the ionicity of TTF-CA in the pressure-temperature phase diagram. At any point, the TTF-CA crystal bears only a single ionicity; there is no coexistence region or an exotic high-pressure phase. Our findings shed new light on the role of electron-phonon interaction in the neutral-ionic transition.