FFLO Excitonic State in the Three-Chain Hubbard Model for Ta${}_2$NiSe${}_5$

Abstract

The three-chain Hubbard model for Ta${}_2$NiSe${}_5$ known as a candidate material for the excitonic insulator is investigated over the wide range of energy gap $D$ between the two-fold degenerate conduction bands and the nondegenerate valence band including both semiconducting ($D>0$) and semimetallic ($D<0$) cases. In the semimetallic case, the difference of the band degeneracy inevitably causes the imbalance of each Fermi wavenumber, resulting in a remarkable excitonic state characterized by the condensation of excitons with finite center-of-mass momentum $q$, the so-called Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) excitonic state. With decreasing $D$ corresponding to increasing pressure, the obtained excitonic phase diagram shows a crossover from BEC ($D\simg 0$) to BCS ($D\siml 0$) regime, and then shows a distinct phase transition at a certain critical value $D_c(<0)$ from the uniform ($q=0$) to the FFLO ($q\ne 0$) excitonic state, as expected to be observed in Ta${}_2$NiSe${}_5$ under high pressure.

5 pages, 4 figures, J. Phys. Soc. Jpn, in press

References in corpus (6)

• Orthorhombic-to-Monoclinic Phase Transition of Ta2NiSe5 Induced by the Bose-Einstein Condensation of Excitons
• Excitonic Bose-Einstein condensation in Ta2NiSe5 above room temperature
• Effects of density imbalance on the BCS-BEC crossover in semiconductor electron-hole bilayers
• Microscopic quantum interference in excitonic condensation of Ta${}_2$NiSe${}_5$
• Quantum condensation in electron-hole bilayers with density imbalance
• Exciton Condensate Modulation in Electron-Hole Bilayers: A Real-Space Visualization

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• Exciton-phonon cooperative mechanism of the triple-$q$ charge-density-wave and antiferroelectric electron polarization in TiSe${}_2$
• Orthorhombic-to-monoclinic transition in Ta${}_2$NiSe${}_5$ due to a zone-center optical phonon instability
• Doping-controlled transition from excitonic insulator to semimetal in Ta${}_2$NiSe${}_5$
• A New Era of Excitonic Insulators
• Disentangling lattice and electronic instabilities in the excitonic insulator candidate Ta${}_2$NiSe${}_5$ by nonequilibrium spectroscopy
• Orbital diamagnetic susceptibility in excitonic condensation phase
• Electric and magnetic multipoles and bond orders in excitonic insulators
• Excitonic Insulator State of the Extended Falicov-Kimball Model in the Cluster Dynamical Impurity Approximation
• Excitonic Phase Diagram of the Three-Chain Hubbard Model for Semiconducting and Semimetallic Ta${}_2$NiSe${}_5$
• Theory of Orbital Susceptibility on Excitonic Insulator
• First- and second-order phase transitions between the uniform and FFLO excitonic states in the three-chain Hubbard model for Ta2NiSe5
• Spin texture and spin current in excitonic phases of the two-band Hubbard model
• FFLO Superconductivity Mediated by Excitonic Fluctuation in Semimetallic Ta${}_2$NiSe${}_5$
• Theory of Thermal Conductivity on Excitonic Insulator
• Elastic Soft Mode and Electric Quadrupole Response in Excitonic Insulator Candidate (Ta${}_{0.952}$V${}_{0.048}$)${}_2$NiSe${}_5$: Contribution of Electron-Phonon Interaction
• Symmetry breaking states in the half-filled two-orbital Hubbard model with crystalline electric field
• Unveiling Excitonic Insulator Signatures in Ta${}_2$NiSe${}_5$