The two-dimensional organic conductor α-(BEDT-TTF)2I3 undergoes a metal-insulator transition at TCO=135 K due to electronic charge ordering. We have conducted time-resolved investigations of its electronic properties in order to explore the field- and temperature-dependent dynamics. At a certain threshold field, the system switches from low-conducting to a high-conducting state, accompanied by a negative differential resistance. Our time-dependent infrared investigations indicate that close to TCO the strong electric field pushes the crystal into a metallic state with optical properties similar to the one for T>TCO. Well into the insulating state, however, at T=80 K, the spectral response evidences a completely different electronically-induced high-conducting state. Applying a two-state model of hot electrons explains the observations by excitation of charge carriers with a high mobility. They resemble the Dirac-like charge-carriers with a linear dispersion of the electronic bands found in α-(BEDT-TTF)2I3 at high-pressure. Extensive numerical simulations quantitatively reproduce our experimental findings in all details.
@article{arxiv.1606.00663,
title = {Electrically-induced phase transition in $\alpha$-(BEDT-TTF)$_2$I$_3$: Indications for high-mobility hot charge carriers},
author = {Tobias Peterseim and Tomislav Ivek and Dieter Schweitzer and Martin Dressel},
journal= {arXiv preprint arXiv:1606.00663},
year = {2016}
}