Unveiling the underlying interactions in Ta2NiSe5 from photo-induced lifetime change

Abstract

We present a generic procedure for quantifying the interplay of electronic and lattice degrees of freedom in photo-doped insulators through a comparative analysis of theoretical many-body simulations and time- and angle-resolved photoemission spectroscopy (TR-ARPES) of the transient response of the candidate excitonic insulator Ta2NiSe5. Our analysis demonstrates that the electron-electron interactions dominate the electron-phonon ones. In particular, a detailed analysis of the TRARPES spectrum enables a clear separation of the dominant broadening (electronic lifetime) effects from the much smaller bandgap renormalization. Theoretical calculations show that the observed strong spectral broadening arises from the electronic scattering of the photo-excited particle-hole pairs and cannot be accounted for in a model in which electron-phonon interactions are dominant. We demonstrate that the magnitude of the weaker subdominant bandgap renormalization sensitively depends on the distance from the semiconductor/semimetal transition in the high-temperature state, which could explain apparent contradictions between various TR-ARPES experiments. The analysis presented here indicates that electron-electron interactions play a vital role (although not necessarily the sole one) in stabilizing the insulating state.

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Cited by in corpus (12)

• Time- and Angle-Resolved Photoemission Studies of Quantum Materials
• Photo-induced nonequilibrium states in Mott insulators
• A New Era of Excitonic Insulators
• Disentangling lattice and electronic instabilities in the excitonic insulator candidate Ta${}_2$NiSe${}_5$ by nonequilibrium spectroscopy
• Advancing time- and angle-resolved photoemission spectroscopy: The role of ultrafast laser development
• Terahertz parametric amplification as a reporter of exciton condensate dynamics
• Hidden excitonic quantum states with broken time-reversal symmetry
• Collective modes and Raman response in Ta${}_2$NiSe${}_5$
• Measuring the ultrafast screening of $U$ in photo-excited charge-transfer insulators with time-resolved X-ray absorption spectroscopy
• Long-lived relaxation channel and exciton-phonon coupling in Ta2NiSe5 via non-degenerate pump-probe spectroscopy
• Probing the collective excitations of excitonic insulators in an optical cavity
• Ab initio Approach to Collective Excitations in Excitonic Insulators