Pressure-Induced Zero-Gap Semiconducting State in Organic Conductor α-(BEDT-TTF)₂I₃ Salt

2006/01/31 by Shinya Katayama, Akito Kobayashi, Yoshikazu Suzumura
Physics and Astronomy · #cond-mat.mtrl-sci

paper · pdf · doi:10.1143/jpsj.75.054705

6 pages, 8 figures, to be published in J. Phys. Soc. Jpn

arxiv created 2006/04/04 · arxiv updated 2009/12/01

Abstract

We show a zero-gap semiconducting (ZGS) state in the quasi-two-dimensional organic conductor α-(BEDT-TTF)₂I₃ salt, which emerges under uniaxial pressure along the a-axis (the stacking axis of the BEDT-TTF molecule). The ZGS state is the state in which a Dirac cone with the band spectrum of a linear dispersion exists around the Fermi point connecting an unoccupied (electron) band with an occupied (hole) band. The spectrum exhibits a large anisotropy in velocity, which depends on the direction from the Fermi point. By varying the magnitude of several transfer energies of a tight-binding model with four sites per unit cell, it is shown that the ZGS state exists in a wide pressure range, and is attributable to the large anisotropy of the transfer energies along the stacking axis.

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