paper

Finite-temperature photoemission in the extended Falicov-Kimball model: a case study for TaNiSe

arXiv:2101.02479 · doi:10.21468/SciPostPhys.10.3.077

Abstract

Utilizing the unbiased time-dependent density-matrix renormalization group technique, we examine the photoemission spectra in the extended Falicov-Kimball model at zero and finite temperatures, particularly with regard to the excitonic insulator state most likely observed in the quasi-one-dimensional material TaNiSe. Working with infinite boundary conditions, we are able to simulate all dynamical correlation functions directly in the thermodynamic limit. For model parameters best suited for TaNiSe the photoemission spectra show a weak but clearly visible two-peak structure, around the Fermi momenta , which suggests that TaNiSe develops an excitonic insulator of BCS-like type. At higher temperatures, the leakage of the conduction-electron band beyond the Fermi energy becomes distinct, which provides a possible explanation for the bare non-interacting band structure seen in time- and angle-resolved photoemission spectroscopy experiments.

23 pages, 9 figures

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