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Effects of Carrier Doping on the Transport in the Dirac Electron System α-(BEDT-TTF)2I3 under High Pressure
Open AccessArticle

Optical Conductivity in a Two-Dimensional Extended Hubbard Model for an Organic Dirac Electron System α-(BEDT-TTF)2I3

1
Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
2
Toyota College, National Institute of Technology, Eisei-cho 2-1, Toyota 471-8525, Japan
*
Author to whom correspondence should be addressed.
Crystals 2018, 8(3), 137; https://doi.org/10.3390/cryst8030137
Received: 25 February 2018 / Revised: 13 March 2018 / Accepted: 14 March 2018 / Published: 16 March 2018
(This article belongs to the Special Issue Advances in Organic Conductors and Superconductors)
The optical conductivity in the charge order phase is calculated in the two-dimensional extended Hubbard model describing an organic Dirac electron system α -(BEDT-TTF) 2 I 3 using the mean field theory and the Nakano-Kubo formula. Because the interband excitation is characteristic in a two-dimensional Dirac electron system, a peak structure is found above the charge order gap. It is shown that the peak structure originates from the Van Hove singularities of the conduction and valence bands, where those singularities are located at a saddle point between two Dirac cones in momentum space. The frequency of the peak structure exhibits drastic change in the vicinity of the charge order transition. View Full-Text
Keywords: Dirac electron; charge order; optical conductivity; organic conductor; α-(BEDT-TTF)2I3 Dirac electron; charge order; optical conductivity; organic conductor; α-(BEDT-TTF)2I3
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Ohki, D.; Matsuno, G.; Omori, Y.; Kobayashi, A. Optical Conductivity in a Two-Dimensional Extended Hubbard Model for an Organic Dirac Electron System α-(BEDT-TTF)2I3. Crystals 2018, 8, 137.

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