Renormalization Effects on Quasi-Two-Dimensional Organic Conductor α-(BEDT-TTF)2I3

The quasi-two-dimensional organic semiconductor \alpha-(BEDT-TTF)2I3 [BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene] has an anisotropic linear dispersion with a zero energy gap near the Fermi level. Owing to the vanishing density of states at the Fermi level, the Coulomb interaction is unscreened in this material. We theoretically study the effect of the long-range Coulomb interaction and the low-energy/long-wavelength behavior of \alpha-(BEDT-TTF)2I3 using the renormalization group analysis. The nearly logarithmic enhancement of the velocity reshapes tilted Dirac cones, and changes the low-temperature behavior. We also show the theoretical calculation for the site-selective spin susceptibility, which can be measured in an NMR experiment.