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

Autori
Ivek, Tomislav ; Čulo, Matija ; Kuveždić, Marko ; Tutiš, Eduard ; Basletić, Mario ; Mihaljević, Branimir ; Tafra, Emil ; Tomić, Silvia ; Löhle, Anja ; Dressel, Martin ; Schweitzer, Dieter ; Korin-Hamzić, Bojana

Izvornik
Physical review. B (2469-9950) 96 (2017), 7; 075141, 9

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
organic conductor ; BEDT-TTF ; charge order ; semimetal ; Hall effect ; inter-pocket scattering ; temperature-dependent gap ; hopping conductivity ; negative magnetoresistance ; disorder ; relaxor-like ferroelectric

Sažetak
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.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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