Electrically induced phase transition inα−(BEDT-TTF)2I3: Indications for Dirac-like hot charge carriers

Autor: Martin Dressel, Tobias Peterseim, Dieter Schweitzer, Tomislav Ivek
Rok vydání: 2016
Předmět:
Zdroj: Physical Review B. 93
ISSN: 2469-9969
2469-9950
Popis: The two-dimensional organic conductor $\ensuremath{\alpha}\text{\ensuremath{-}}{(\text{BEDT-TTF})}_{2}{\mathrm{I}}_{3}$ undergoes a metal-insulator transition at ${T}_{\mathrm{CO}}=135\phantom{\rule{4.pt}{0ex}}\mathrm{K}$ 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 a low-conducting to a high-conducting state, accompanied by a negative differential resistance. Our time-dependent infrared investigations indicate that close to ${T}_{\mathrm{CO}}$, the strong electric field pushes the crystal into a metallic state with optical properties similar to the one for $Tg{T}_{\mathrm{CO}}$. Well into the insulating state, however, at $T=80\phantom{\rule{4.pt}{0ex}}\mathrm{K}$, 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 $\ensuremath{\alpha}\text{\ensuremath{-}}{(\text{BEDT-TTF})}_{2}{\mathrm{I}}_{3}$ at high pressure. Extensive numerical simulations quantitatively reproduce our experimental findings in all details.
Databáze: OpenAIRE
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