Anomalous Conductivity of Two-Dimensional Dirac Electrons in Organic Conductor under Pressure

The electric conductivity of Dirac electrons in the organic conductor ?-(BEDT-TTF)2I3 [BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene] under pressure has been examined using a two-dimensional tight-binding (TB) model with both impurity and electron–phonon (e–p) scatterings. We study an anomalous temperature dependence conductivity, which shows crossover from ?x < ?y at low temperatures [region (I)] to > high (II)]. are diagonal conductivities parallel perpendicular stacking axis molecules, respectively. effect cone tilting is dominant region (I), whereas anisotropy velocity (II). Such behavior further by calculating deviation principal axes due off-diagonal ?xy nearly constant e–p scattering, extension previous result simple two-band [Phys. Rev. B 98, 161205 (2018)]. relevance experiments conductors discussed.