Gap opening mechanism for correlated Dirac electrons in organic compounds $\alpha$-(BEDT-TTF)${}_2$I${}_3$ and $\alpha$-(BEDT-TSeF)${}_2$I${}_3$

Abstract

To determine how electron correlations open a gap in two-dimensional massless Dirac electrons in the organic compounds $\alpha$-(BEDT-TTF)${}_2$I${}_3$ [$\alpha$-(ET)${}_2$I${}_3$] and $\alpha$-(BEDT-TSeF)${}_2$I${}_3$ [$\alpha$-(BETS)${}_2$I${}_3$], we derive and analyze $ab$ $initio$ low-energy effective Hamiltonians for these two compounds. We find that the horizontal stripe charge ordering opens a gap in the massless Dirac electrons in $\alpha$-(ET)${}_2$I${}_3$, while an insulating phase without explicit symmetry breaking appears in $\alpha$-(BETS)${}_2$I${}_3$. We clarify that the combination of the anisotropic transfer integrals and the electron correlations induces a dimensional reduction in the spin correlations, i.e., one-dimensional spin correlations develop in $\alpha$-(BETS)${}_2$I${}_3$. We show that the one-dimensional spin correlations open a gap in the massless Dirac electrons. Our finding paves the way for opening gaps for massless Dirac electrons using strong electronic correlations.

9 pages, 2 tables, and 6 figures. The input and output files of the ab initio and the mVMC calculations are available at https://isspns-gitlab.issp.u-tokyo.ac.jp/k-yoshimi/alpha-salts

References in corpus (17)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Topological Mott Insulators
• Quantum spin-liquid emerging in two-dimensional correlated Dirac fermions
• Tilted anisotropic Dirac cones in quinoid-type graphene and alpha-(BEDT-TTF)_2I_3
• Absence of a Spin Liquid Phase in the Hubbard Model on the Honeycomb Lattice
• Charge Ordering in alpha-(BEDT-TTF)2I3 by synchrotron x-ray diffraction
• Electronic Structure Calculation by First Principles for Strongly Correlated Electron Systems
• 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
• Ab initio two-dimensional multiband low-energy models of EtMe_3Sb[Pd(dmit)_2]_2 and κ-(BEDT-TTF)_2Cu(NCS)_2 with comparisons to single-band models
• Correlation Effects on Charge Order and Zero-Gap State in the Organic Conductor α-(BEDT-TTF)2I3
• Unconventional dual 1D-2D quantum spin liquid revealed by $ab$ $initio$ studies on organic solids family
• Spin excitations in the quasi-two-dimensional charge-ordered insulator $\alpha$-(BEDT-TTF)${}_2$I${}_3$ probed via ${}^{13}$C NMR
• $Ab$ $initio$ derivation and exact-diagonalization analysis of low-energy effective Hamiltonians for ${\beta }^{\prime }$-X[Pd(dmit)${}_2$]${}_2$
• Pressure-induced phase switching of the Shubnikov de Haas oscillations in molecular Dirac fermion system $\alpha -$(BETS)${}_2$I${}_3$
• Interaction-induced quantum spin Hall insulator in the organic Dirac electron system $\alpha$-(BEDT-TSeF)${}_2$I${}_3$
• Electric and Magnetic Responses of Two-dimensional Dirac Electrons in Organic Conductor $\alpha$-(BETS)${}_2$I${}_3$

Cited by in corpus (5)

• Thermal difference reflectivity of tilted 2D Dirac materials
• Pressure-induced topological changes in Fermi surface of two-dimensional molecular conductor
• Combined X-ray diffraction, electrical resistivity, and $ab$ $initio$ study of (TMTTF)${}_2$PF${}_6$ under pressure: implications to the unified phase diagram
• Ambient-Pressure Organic Dirac Electron State in $\alpha$-(BETS)${}_2$AuCl${}_2$
• Charge-localization-driven metal-insulator phase transition in layered molecular conductors