Seebeck Effect of Dirac Electrons in Organic Conductors under Hydrostatic Pressure Using a TightBinding Model Derived from First Principles
Abstract
The Seebeck coefficient is examined for twodimensional Dirac electrons in the threequarter filled organic conductor α(BEDTTTF)_{2}I_{3} [BEDTTTF denotes bis(ethylenedithio)tetrathiafulvalene] under hydrostatic pressure, where the Seebeck coefficient S is proportional to the ratio of the thermoelectric conductivity L_{12} to the electrical conductivity L_{11}, i.e., S = L_{12}/TL_{11} with T being the temperature. We present an improved tightbinding model in two dimensions with transfer energies determined from firstprinciples density functional theory calculations with an experimentally determined crystal structure. The T dependence of the Seebeck coefficient is calculated by adding impurity and electronphonon scatterings. Noting a zerogap state due to the Dirac cone, which results in a competition from contributions between the conduction and valence bands, we show positive S_{x} and S_{y} at finite temperatures and analyze them in terms of spectral conductivity. The relevance of the calculated S_{x} (perpendicular to the molecular stacking axis) to the experiment is discussed.
 Publication:

Journal of the Physical Society of Japan
 Pub Date:
 May 2024
 DOI:
 10.7566/JPSJ.93.054704
 arXiv:
 arXiv:2404.05914
 Bibcode:
 2024JPSJ...93e4704S
 Keywords:

 Condensed Matter  Mesoscale and Nanoscale Physics
 EPrint:
 7 pages,12 figures