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arXiv · 1810.13079

Anisotropy of Dirac cones and van Hove singularity in an organic Dirac fermion system

Ayaka Mori·Mitsuyuki Sato·Takeshi Yajima·Takako Konoike·Kazuhito Uchida·Toshihito Osada
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Abstract

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.

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Ayaka Mori, Mitsuyuki Sato, Takeshi Yajima, Takako Konoike, Kazuhito Uchida, Toshihito Osada. 2018-10-31. Anisotropy of Dirac cones and van Hove singularity in an organic Dirac fermion system. https://doi.org/10.1103/physrevb.99.035106

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