Anomalous orbital magnetism and Hall effect of massless Fermions in two dimension

Inter-band effects of magnetic field on orbital magnetic susceptibility and Hall effect in weak magnetic field have been studied theoretically at absolute zero for the model of massless Fermions in two dimension described by Weyl equation similar to graphenes, which are simplified version of newly-found one in molecular solids, alpha-ET2I3, described by the tilted Weyl equation. The dependences on the Fermi energy of both orbital susceptibility and Hall conductivity near the zero-gap region scale with the elastic scattering time and then are very singular.