ARTICLE | doi:10.20944/preprints201802.0159.v1
Subject: Physical Sciences, Condensed Matter Physics Keywords: Dirac electron; charge order; optical conductivity; organic conductor; α-(BEDT-TTF)2I3
Online: 26 February 2018 (10:39:40 CET)
The optical conductivity in the charge order phase is calculated in the extended Hubbard model describing an organic Dirac electron system α-(BEDT-TTF)2I3 using the mean field theory and the Nakano-Kubo formula. A peak structure due to interband excitation being characteristic in two-dimensional Dirac electron system 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.