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arXiv · 2211.00966

Seebeck Coefficient of Two-dimensional Dirac Electrons in Organic Conductor under Pressure

Yoshikazu Suzumura·Masao Ogata
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Abstract

The Seebeck coefficient, which is proportional to a ratio of the thermoelectric conductivity to electrical conductivity has been examined for Dirac electrons in the organic conductor $\alpha$-(BEDT-TTF)$_2$I$_3$ [BEDT-TTF denotes a molecule given by bis(ethylenedithio)tetrathiafulvalene] under a uniaxial pressure using a two-dimensional tight-binding model with both impurity and electron--phonon (e--p) scatterings. We calculate an anomalous temperature ($T$) dependence of the Seebeck coefficient $S_{\nu}$ with $\nu = x$ (perpendicular to the molecular stacking axis) and $y$, which shows $S_\nu > 0$ with a maximum at high temperatures and $S_{\nu} < 0$ with a minimum at low temperatures.The microscopic mechanism of such a sign change of $S_\nu$ is clarified in terms of the spectral conductivity. The result is compared with experiments on $\alpha$-(BEDT-TTF)$_2$I$_3$.

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Yoshikazu Suzumura, Masao Ogata. 2022-11-02. Seebeck Coefficient of Two-dimensional Dirac Electrons in Organic Conductor under Pressure. https://doi.org/10.1103/physrevb.107.195416

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