Dresden 2014 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 80: Low-Dimensional Systems - Poster Session

TT 80.19: Poster

Wednesday, April 2, 2014, 15:00–19:00, P2

Photo-induced phase transition in α-(BEDT-TTF)₂I₃ probed by FTIR and photoconductivity measurements — •Tobias Peterseim, Patricia Haremski, Tomislav Ivek, and Martin Dressel — 1. Physikalisches Institut, Universität Stuttgart, Germany

In recent years, the study of nonequilibrium states generated by external stimuli, for instance photo-induced phase transition (PIPT), gained a lot of attention as they shed new light on the physics of the equilibrium state in various materials classes. Furthermore, the observed PIPT show potential routes to build new electronic devices for the application, i.e. optical switches or volatile memories.

The 2D organic salt α-(BEDT-TTF)₂I₃ is such a candidate in the class of molecular conductors revealing a metal-insulator phase transition at 136 K. It is accompanied by a charge disproportionation between the different molecular sites. We investigated the photoresponse of α-(BEDT-TTF)₂I₃ in the charged-ordered state. The observed photocurrent shows a non-exponential decay with a residual conductivity. Furthermore, it exhibits a distinct dependency on the laser intensity and the applied electric field including a delayed switching into a high conducting state. Additionally, we performed time-dependent FTIR measurements where traces of a photo-induced metallic phase could be observed. Its decay is in accordance with the photocurrent measurements. However, no indication for the residual conductivity could be found in the time-dependent infrared spectra. We will suggest a possible model which explains the observations.