The electronic structure of weak charge-ordering (CO) state just below the critical pressure in an organic conductor \alpha-(BEDT-TTF)_2I_3 was experimentally investigated using peak structure in the temperature dependence of interlayer magnetoresistance (MR). Based on a minimal model considering multiple Landau levels (LLs), we discuss herein the MR peak as characteristic to multilayer massless/massive Dirac fermion (DF) systems. MR measured in the weak CO state exhibited a clear MR peak, and its magnetic-field dependence was consistent with the LL behavior of a massive DF with a small gap. Results indicate that the weak CO state in \alpha-(BEDT-TTF)_2I_3 is a massive DF state.
@article{arxiv.2101.06447,
title = {Experimental Confirmation of Massive Dirac Fermions in Weak Charge-Ordering State in \alpha-(BEDT-TTF)_2I_3},
author = {Kenta Yoshimura and Mitsuyuki Sato and Toshihito Osada},
journal= {arXiv preprint arXiv:2101.06447},
year = {2021}
}