Spin-Orbit Coupling Effect on the Seebeck Coefficient in Dirac Electron Systems in $\alpha$-(BETS)${}_2$I${}_3$

Abstract

The Seebeck coefficient, $S=L_{12}/(T{L}_{11})$, 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, $\alpha$-(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 $L_{11}$

12pages, 12figures

References in corpus (28)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Two-Dimensional Gas of Massless Dirac Fermions in Graphene
• Advanced capabilities for materials modelling with Quantum ESPRESSO
• Maximally-localized generalized Wannier functions for composite energy bands
• Maximally-localized Wannier functions for entangled energy bands
• Electronic Properties of Disordered Two-Dimensional Carbon
• Pressure-Induced Zero-Gap Semiconducting State in Organic Conductor $\alpha$-(BEDT-TTF)${}_2$I${}_3$ Salt
• Tilted anisotropic Dirac cones in quinoid-type graphene and alpha-(BEDT-TTF)_2I_3
• First-Principles Study of Electronic Structure in $\alpha$-(BEDT-TTF)${}_2$I${}_3$ at Ambient Pressure and with Uniaxial Strain
• Observation of an anisotropic Dirac cone reshaping and ferrimagnetic spin polarization in an organic conductor
• Importance of Spin-Orbit Coupling in Organic BEDT-TTF and BEDT-TSF Salts
• Electronic Properties Close to Dirac Cone in Two-Dimensional Organic Conductor $\alpha$-(BEDT-TTF)${}_2$I${}_3$
• Insulating nature of strongly correlated massless Dirac fermions in an organic crystal
• Electric Conductivity of the Zero-gap Semiconducting State in Alpha-(BEDT-TTF)2I3 Salt
• Inter-Band Effects of Magnetic Field on Hall Conductivity in Multi Layered Massless Dirac Fermion System $\alpha$-(BEDT-TTF)${}_2$I${}_3$
• Ambient pressure Dirac electron system in quasi-two-dimensional molecular conductor $\alpha$-(BETS)${}_2$I${}_3$
• First-principles study of the effective Hamiltonian for Dirac fermions with spin-orbit coupling in two-dimensional molecular conductor $\alpha$-(BETS)${}_2$I${}_3$
• Large Diamagnetism and Electromagnetic Duality in Two-dimensional Dirac Electron System
• Topological Insulator State due to Finite Spin-Orbit Interaction in an Organic Dirac Fermion System
• Transport properties of organic Dirac electron system α-(BEDT-TSeF)${}_2$I${}_3$
• Interaction-induced quantum spin Hall insulator in the organic Dirac electron system $\alpha$-(BEDT-TSeF)${}_2$I${}_3$
• Anomalous Spin Transport Properties of Gapped Dirac Electrons with Tilting
• Role of acoustic phonons in exotic conductivity of two-dimensional Dirac electrons
• Electric and Magnetic Responses of Two-dimensional Dirac Electrons in Organic Conductor $\alpha$-(BETS)${}_2$I${}_3$
• Effect of Coulomb Interaction on Seebeck Coefficient of Organic Dirac Electron System $\alpha$-(BEDT-TTF)${}_2$I${}_3$
• Anomalous conductivity of two-dimensional Dirac electrons in organic conductor under pressures
• Seebeck Effect of Dirac Electrons in Organic Conductors under Hydrostatic Pressure Using a Tight-Binding Model Derived from First Principles
• Seebeck Coefficient of Two-dimensional Dirac Electrons in Organic Conductor under Pressure