We propose an experimental method to examine the in-plane anisotropy of electronic structure in layered conductors. In the method, we measure the interlayer magnetoresistance as a function of in-plane magnetic field orientation. We applied it to an organic Dirac fermion system a-(BEDT-TTF)2I3 to experimentally determine the orientation of the anisotropic Dirac cones. It is concluded that the long axis of the elliptic constant-energy contours of the Dirac cone is tilted by approximately -30 deg from the crystalline a-axis to b-axis under hydrostatic pressures. Additionally, we observed a signature of van Hove singularity (which is a saddle point of the band dispersion) at 30-40 K above or below the Dirac point. The ridgeline of the saddle point is estimated as almost parallel to the crystalline b-axis.
@article{arxiv.1810.13079,
title = {Anisotropy of Dirac cones and van Hove singularity in an organic Dirac fermion system},
author = {Ayaka Mori and Mitsuyuki Sato and Takeshi Yajima and Takako Konoike and Kazuhito Uchida and Toshihito Osada},
journal= {arXiv preprint arXiv:1810.13079},
year = {2019}
}