Specific Heat of the Multilayered Massless Dirac Fermion System

Abstract

We have measured the specific heat of the multilayered massless Dirac fermion system α-(BEDT-TTF) 2 I 3 under pressure. The temperature dependence of the specific heat is almost quadratic at low temperature, suggesting massless Dirac dispersion in this system. In a magnetic field, the specific heat shows anomalous behavior, which can be understood by assuming the zero-mode Landau level characteristic of the Dirac fermion system and its spin splitting. These results are in good agreement with the reported magnetoresistance.