Spin-Orbit Coupling Effect on the Seebeck Coefficient in Dirac Electron Systems in $α$-(BETS)$_2$I$_3$
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866912714655268864 |
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| author | Suzumura, Yoshikazu Tsumuraya, Takao Ogata, Masao |
| author_facet | Suzumura, Yoshikazu Tsumuraya, Takao Ogata, Masao |
| contents | The Seebeck coefficient, $S=L_{12}/(TL_{11})$, which is proportional to a ratio of the thermoelectric conductivity $L_{12}$ to the electric conductivity $L_{11}$ with $T$ being temperature is examined for two-dimensional Dirac electrons in the three-quarter filled organic conductor, $α$-(BETS)$_2$I$_3$, [BETS = BEDT-TSeF = bis(ethylenedithio)tetraselenafulvalene] at ambient pressure.Using a tight-binding model obtained with the first-principles relativistic density-functional theory method [Tsumuraya and Suzumura, Eur. Phys. J. B 94, 17 (2021)], we calculate $S$ in the presence of the impurity and electron--phonon scatterings. We show that $S_x < 0$ and $S_y >0$ at high temperatures, where $S_x$ ($S_y$) denotes $S$ perpendicular (parallel) to the molecular stacking axis. There is a sign change of $S_y$ with increasing $T$. We find that, at low temperatures the absolute value of $S$ is enhanced by the spin-orbit coupling. The Seebeck coefficient is examined by dividing it into components of the conduction and valence bands; we find that the electron and hole contributions compete with each other. Such $T$ dependence of $S$ is clarified using the spectral conductivity, which determines $L_{12}$ and $L_{11}$ |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2509_07349 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Spin-Orbit Coupling Effect on the Seebeck Coefficient in Dirac Electron Systems in $α$-(BETS)$_2$I$_3$ Suzumura, Yoshikazu Tsumuraya, Takao Ogata, Masao Mesoscale and Nanoscale Physics The Seebeck coefficient, $S=L_{12}/(TL_{11})$, which is proportional to a ratio of the thermoelectric conductivity $L_{12}$ to the electric conductivity $L_{11}$ with $T$ being temperature is examined for two-dimensional Dirac electrons in the three-quarter filled organic conductor, $α$-(BETS)$_2$I$_3$, [BETS = BEDT-TSeF = bis(ethylenedithio)tetraselenafulvalene] at ambient pressure.Using a tight-binding model obtained with the first-principles relativistic density-functional theory method [Tsumuraya and Suzumura, Eur. Phys. J. B 94, 17 (2021)], we calculate $S$ in the presence of the impurity and electron--phonon scatterings. We show that $S_x < 0$ and $S_y >0$ at high temperatures, where $S_x$ ($S_y$) denotes $S$ perpendicular (parallel) to the molecular stacking axis. There is a sign change of $S_y$ with increasing $T$. We find that, at low temperatures the absolute value of $S$ is enhanced by the spin-orbit coupling. The Seebeck coefficient is examined by dividing it into components of the conduction and valence bands; we find that the electron and hole contributions compete with each other. Such $T$ dependence of $S$ is clarified using the spectral conductivity, which determines $L_{12}$ and $L_{11}$ |
| title | Spin-Orbit Coupling Effect on the Seebeck Coefficient in Dirac Electron Systems in $α$-(BETS)$_2$I$_3$ |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2509.07349 |