Non-Coulomb strong electron-hole binding in $T{a}_{2}NiS{e}_5$ revealed by time- and angle-resolved photoemission spectroscopy

Abstract

We reveal an ultrafast purely electronic phase transition in \TNS, which is a plausible excitonic insulator, after excited by an ultrafast infrared laser pulse. Specifically, the order parameter of the strong electron-hole binding shrinks with enhancing the pump pulse, and above a critical pump fluence, a photo-excited semimetallic state is experimentally identified with the absence of ultrafast structural transition. In addition, the bare valence and conduction bands and also the effective exciton binding energy in \TNS~are determined. These findings and detailed analysis suggest a bare nonequilibrium semimetallic phase in $T{a}_{2}NiS{e}_5$ and the strong electron-hole binding cannot be exclusively driven by Coulomb interaction.

arXiv comment18 pages, 10 figures

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Cited by in corpus (34)

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• Role of electron-phonon coupling in excitonic insulator candidate Ta2NiSe5
• A New Era of Excitonic Insulators
• Nonlinear spectroscopy of collective modes in excitonic insulator
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• Signatures of ultrafast reversal of excitonic order in Ta${}_2$NiSe${}_5$
• Advancing time- and angle-resolved photoemission spectroscopy: The role of ultrafast laser development
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• Ultrafast Switching from the Charge Density Wave Phase to a Metastable Metallic State in 1T-TiSe${}_2$
• Terahertz parametric amplification as a reporter of exciton condensate dynamics
• Evidence for an Excitonic Insulator State in Ta${}_2$Pd${}_3$Te${}_5$
• Evolution of the electronic structure in Ta${}_2$NiSe${}_5$ across the structural transition revealed by resonant inelastic x-ray scattering
• Photoinduced metallization of excitonic insulators
• Finite-temperature photoemission in the extended Falicov-Kimball model: a case study for Ta${}_2$NiSe${}_5$
• Pressure suppression of the excitonic insulator state in Ta2NiSe5 observed by optical conductivity
• Anomalous contribution to the nematic electronic states from the structural transition in FeSe revealed by time- and angle-resolved photoemission spectroscopy
• Theory of time-crystalline behaviour mediated by phonon squeezing in Ta2NiSe5
• Excitonic insulator phase and dynamics of condensate in a topological one-dimensional model
• Photo-induced Dirac cone flattening in BaNiS${}_2$
• Collective modes and Raman response in Ta${}_2$NiSe${}_5$
• Identification of metastable lattice distortion free charge density wave at photoinduced interface via TRARPES
• Photo-induced Dynamics of Quasicrystalline Excitonic Insulator
• Analysis methodology of coherent oscillations in time- and angle-resolved photoemission spectroscopy
• Gate tuning of coupled electronic and structural phase transition in atomically thin Ta${}_2$NiSe${}_5$
• Strong long-wavelength electron-phonon coupling in Ta${}_2$Ni(Se,S)${}_5$
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• Nonequilibrium Dynamics in a Quantum Spin Chain with Pump-Probe Resonant Inelastic X-ray Scattering
• Probing the collective excitations of excitonic insulators in an optical cavity