Temperature Dependence of Inter-Layer Longitudinal Magnetoresistance in α-(BEDT-TTF)2I3: Positive versus Negative Contributions in a Tilted Dirac Cone System

Temperature depedence of the longitudinal interlayer magnetoresistance (MR) of a bulk Dirac cone system, α-(BEDT-TTF) 2 I 3 , is examined. It exhibits a peak related to the crossover from the quantum limit regime with negative MR at low temperatures to the inter-level scattering regime with positive MR at higher temperatures. The field dependence of the MR peak temperature, which measures the energy separation between the n = 0 and ±1 Landau levels, evidences that the peculiar Landau quantization of the Dirac cone dispersion is relevant to both effects. The effective Fermi velocity, v eff , which reflects the width and spacing of the Landau levels, has been estimated from the analysis taking account of the Zeeman-split Landau levels.