Electron-Phonon Coupling Mode in Excitonic Insulator

Abstract

Ta2NiSe5 is considered a promising excitonic insulator (EI) candidate with slight phonon contributions, since it exhibits a tiny orthorhombic-to-monoclinic structural distortion at 328 K without any superlattice structure. Our synchrotron inelastic x-ray scattering measurements reveal strong electron-optical-phonon coupling occurring at temperatures higher than the transition temperature. Density functional theoretical calculations indicate that two coupled optical modes arise due to the vibration of Ta and Se ions. Further, the two modes are frozen such that Ta and Se approach each other, forming atomic-displacement-type electric dipoles in the monoclinic phase. The characteristic of electronic toroidal moment formation by the antiferro-arrangements of electric dipoles is the universality of EI between Ta2NiSe5 and 1T-TiSe2.

arXiv comment6 pages, 3 figures

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Cited by in corpus (39)

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• Direct observation of excitonic instability in Ta2NiSe5
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• Non-Coulomb strong electron-hole binding in $T{a}_{2}NiS{e}_5$ revealed by time- and angle-resolved photoemission spectroscopy
• Collective Modes in Excitonic Insulators: Effects of Electron-Phonon Coupling and Signatures in Optical Response
• Orthorhombic-to-monoclinic transition in Ta${}_2$NiSe${}_5$ due to a zone-center optical phonon instability
• Phononic soft mode and strong electronic background behavior across the structural phase transition in the excitonic insulator Ta${}_2$NiSe${}_5$ (with Erratum)
• Critical charge fluctuations and emergent coherence in a strongly correlated excitonic insulator
• Evidence of ideal excitonic insulator in bulk MoS2 under pressure
• Lattice dynamics of the excitonic insulator Ta${}_2$Ni(Se${}_{1-x}$S${}_x$)${}_5$
• Role of electron-phonon coupling in excitonic insulator candidate Ta2NiSe5
• Hybridization-gap Formation and Superconductivity in the Pressure-induced Semimetallic Phase of the Excitonic Insulator Ta${}_2$NiSe${}_5$
• Effect of Cu intercalation and pressure on excitonic interaction in 1T-TiSe2
• A New Era of Excitonic Insulators
• Signatures of ultrafast reversal of excitonic order in Ta${}_2$NiSe${}_5$
• Disentangling lattice and electronic instabilities in the excitonic insulator candidate Ta${}_2$NiSe${}_5$ by nonequilibrium spectroscopy
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• Terahertz parametric amplification as a reporter of exciton condensate dynamics
• Room Temperature Thermoelectric Properties of Isostructural Selenides Ta2PdS6 and Ta2PdSe6
• Photoinduced electron-electron pairing in the extended Falicov-Kimball model
• Unconventional Charge-density-wave Order in a Dilute d-band Semiconductor
• Tunneling-tip-induced collapse of the charge gap in the excitonic insulator Ta${}_2$NiSe${}_5$
• Finite-temperature photoemission in the extended Falicov-Kimball model: a case study for Ta${}_2$NiSe${}_5$
• Thermal transport signatures of the excitonic transition and associated phonon softening in the layered chalcogenide Ta${}_2$NiSe${}_5$
• Excitonic Instability in Ta2Pd3Te5 Monolayer
• Excitonic Insulator to Superconductor Phase Transition in Ultra-Compressed Helium
• Third-harmonic generation in excitonic insulators
• Theory of time-crystalline behaviour mediated by phonon squeezing in Ta2NiSe5
• Optically induced symmetry breaking due to nonequilibrium steady state formation in charge density wave material 1T-TiSe2
• FFLO Superconductivity Mediated by Excitonic Fluctuation in Semimetallic Ta${}_2$NiSe${}_5$
• Electronic and Optical Properties of Ta${}_2$NiSe${}_5$ Monolayer: A First-principles Study
• Detecting photoelectrons from spontaneously formed excitons
• Strong long-wavelength electron-phonon coupling in Ta${}_2$Ni(Se,S)${}_5$
• Gate tuning of coupled electronic and structural phase transition in atomically thin Ta${}_2$NiSe${}_5$
• 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
• Comment on "Direct observation of excitonic instability in Ta${}_2$NiSe${}_5$" [arXiv:2007.08212 (2020)]
• Unusual temperature dependence of the band structure associated with local atomic distortion in monolayer 1T'-WTe2
• Stabilization of sliding ferroelectricity through exciton condensation
• Long-lived relaxation channel and exciton-phonon coupling in Ta2NiSe5 via non-degenerate pump-probe spectroscopy