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

Scientific paper - Original scientific paper

• Author: Tomislav Ivek; MBZ: 261996
• Author: Matija Čulo; MBZ: 315094
• Author: Marko Kuveždić; MBZ: 352683
• Author: Eduard Tutiš; MBZ: 18035
• Author: Mario Basletić; MBZ: 197593
• Author: Branimir Mihaljević
• Author: Emil Tafra; MBZ: 248700
• Author: Silvia Tomić; MBZ: 65594
• Author: Anja Löhle
• Author: Martin Dressel
• Author: Dieter Schweitzer
• Author: Bojana Korin-Hamzić
• Author's institution: University of Zagreb; Faculty of Science; (Department of Physics)
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract (english)

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.

• Keywords (english): organic conductor; BEDT-TTF; charge order; semimetal; Hall effect; inter-pocket scattering; temperature-dependent gap; hopping conductivity; negative magnetoresistance; disorder; relaxor-like ferroelectric
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: Physical Review B
• Numbering: vol. 96, no. 7, 075141
• p-ISSN: 2469-9950
• e-ISSN: 2469-9969
• DOI: https://doi.org/10.1103/PhysRevB.96.075141
• URN:NBN: urn:nbn:hr:217:056541
• Publication: 2017
• Project: Number: IP-2013-11-1011; Title (croatian): Jako korelirani elektroni u slojnim organskim materijalima i manganitima: niskofrekventna pobuđenja i nelinearna dinamika; Acronym: SCEinLOM; Leader: Silvia Tomić; Jurisdiction: Croatia; Funding stream: IP
• Document URL: https://journals.aps.org/prb/abstract/10.1103/PhysRevB.96.075141
• Type of resource: Text
• Access conditions: Open access
• Public note: © 2017 American Physical Society. Received 8 March 2017. Revised manuscript received 11 July 2017. Published 21 August 2017.
• Created on: 2020-02-29 18:42:33