Semimetallic and charge-ordered α-(BEDT-TTF)2I3: On the role of disorder in dc transport and dielectric properties

Ivek, Tomislav and Čulo, Matija and Kuveždić, Marko and Tutiš, Eduard and Basletić, Mario and Mihaljević, Branimir and Tafra, Emil and Tomić, Silvia and Lohle, Anja and Dressel, Martin and Schweitzer, Dieter and Korin-Hamzić, Bojana (2017) Semimetallic and charge-ordered α-(BEDT-TTF)2I3: On the role of disorder in dc transport and dielectric properties. Physical Review B, 96 (7). pp. 75141-9. ISSN 1098-0121

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α-(BEDT-TTF)2I3 is a prominent example of charge ordering among organic conductors. In this work, we explore the details of transport within the charge-ordered as well as semimetallic phase at ambient pressure. In the high-temperature semimetallic phase, the mobilities and concentrations of both electrons and holes conspire in such a way to create an almost temperature-independent conductivity as well as a low Hall effect. We explain these phenomena as a consequence of a predominantly interpocket scattering which equalizes mobilities of the two types of charge carriers. At low temperatures, within the insulating charge-ordered phase two channels of conduction can be discerned: a temperature-dependent activation, which follows the mean-field behavior, and a nearest-neighbor-hopping contribution. Together with negative magnetoresistance, the latter relies on the presence of disorder. The charge-ordered phase also features a prominent dielectric peak which bears a similarity to relaxor ferroelectrics. Its dispersion is determined by free-electron screening and pushed by disorder well below the transition temperature. The source of this disorder can be found in the anion layers which randomly perturb BEDT-TTF molecules through hydrogen bonds.

Item Type: Article
Date: 21 August 2017
Subjects: NATURAL SCIENCES > Physics
Additional Information: © 2017 American Physical Society. Received 8 March 2017. Revised manuscript received 11 July 2017. Published 21 August 2017.
Divisions: Faculty of Science > Department of Physics
Publisher: American Physical Society
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 17 Sep 2017 20:27
Last Modified: 17 Sep 2017 20:28

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