Valence-bond insulator in proximity to excitonic instability

Chiba, Yuuya; Mitsuoka, Takumi; Saini, N. L.; Horiba, Koji; Kobayashi, Masaaki; Ono, Kanta; Kumigashira, Hiroshi; Katayama, Naoyuki; Sawa, Hiroshi; Nohara, M.; Lu, Yangfan; Takagi, H.; Mizokawa, T.

doi:10.1103/physrevb.100.245129

Cited by 12 publications

(7 citation statements)

References 42 publications

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“…Such leakage reflects the intensity tail above E F after pumping observed in a recent t-ARPES experiment for Ta 2 NiSe 5 [19]. Likewise we should verify in terms of the EFKM that the upper band in the PES at T > 0 is missing or merged into a single band due to the small value of U, just as indicated by ARPES on Ta 2 NiSe 5 [11,12,21].…”

Section: Photoemission Spectra At Finite Temperaturessupporting

confidence: 66%

“…Motivated by this, various experiments have recently performed for this material, using NMR [14], inelastic xray scattering [15], scanning tunneling microscopy or spectroscopy [16,17], and time-and angle-resolved photoemission spectroscopy (t-ARPES) [18][19][20]. Besides there is the isostructual compound Ta 2 NiS 5 , which opens up the possibility to perform comparative measurements and analysis, not only of the photoemission [21] but also of the magnetic susceptibility [10] and the optical conductivity [22,23].…”

Section: Introductionmentioning

confidence: 99%

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Finite-temperature photoemission in the extended Falicov-Kimball model: a case study for Ta$_2$NiSe$_5$

Lange

Fehske

2021

SciPost Phys.

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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 Ta_22NiSe_55. 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 Ta_22NiSe_55 the photoemission spectra show a weak but clearly visible two-peak structure, around the Fermi momenta k\simeq\pm k_{F}k≃±kF, which suggests that Ta_22NiSe_55 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.

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Section: Photoemission Spectra At Finite Temperaturessupporting

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Finite-temperature photoemission in the extended Falicov-Kimball model: a case study for Ta$_2$NiSe$_5$

Lange

Fehske

2021

SciPost Phys.

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“…Intriguingly, substitution of Se with S has been shown to suppress T c in transport experiments to zero [19], suggesting a possible quantum phase transition (QPT) at x = x c in Ta 2 Ni(Se 1−x S x ) 5 . Increasing x enhances the band gap in the electronic structure [35], which is known to suppress the EI [27,28], consistent with an EI QPT. On the other hand, the lattice degrees of freedom also evolve with x making it imperative to separately assess the roles of electronic and lattice degrees of freedom throughout the phase diagram of Ta 2 Ni(Se 1−x S x ) 5 .…”

mentioning

confidence: 53%

“…The suppression of the excitonic instability with x is even more evident in Ta 2 NiS 5 , Fig. 1(d,h,i), where the low-energy electronic response is altogether absent due to a direct band gap [35]. Instead, we observe a sharp B 2g -symmetry mode at 0.3 eV, Fig.…”

mentioning

confidence: 67%

Failed excitonic quantum phase transition in Ta$_2$Ni(Se$_{1-x}$S$_x$)$_5$

Volkov,

Ye,

Lohani

et al. 2021

Preprint

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We study the electronic phase diagram of the excitonic insulator candidates Ta2Ni(Se1−xSx)5 [x=0, ... ,1] using Raman spectroscopy. Critical excitonic fluctuations are observed, that diminish with x and ultimately shift to high energies, characteristic of a quantum phase transition. Nonetheless, a symmetry-breaking transition at finite temperatures is detected for all x, exposing a cooperating lattice instability that takes over for large x. Our study reveals a failed excitonic quantum phase transition, masked by a preemptive structural order.

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“…Motivated by this, various experiments have recently performed for this material, using NMR [14], inelastic x-ray scattering [15], scanning tunneling microscopy or spectroscopy [16,17], and time-and angleresolved photoemission spectroscopy (t-ARPES) [18][19][20]. Besides there is the isostructual compound Ta 2 NiS 5 , which opens up the possibility to perform comparative measurements and analysis, not only of the photoemission [21] but also of the magnetic susceptibility [10] and the optical conductivity [22,23].…”

mentioning

confidence: 99%

Finite-temperature photoemission in the extended Falicov-Kimball model: a case study for Ta$_2$NiSe$_5$

Ejima,

Lange,

Fehske

2021

Preprint

View full text Add to dashboard Cite

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 Ta 2 NiSe 5 . 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 Ta 2 NiSe 5 the photoemission spectra show a weak but clearly visible two-peak structure, around the Fermi momenta k ±k F , which suggests that Ta 2 NiSe 5 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.

show abstract

Valence-bond insulator in proximity to excitonic instability

Cited by 12 publications

References 42 publications

Finite-temperature photoemission in the extended Falicov-Kimball model: a case study for Ta$_2$NiSe$_5$

Finite-temperature photoemission in the extended Falicov-Kimball model: a case study for Ta$_2$NiSe$_5$

Failed excitonic quantum phase transition in Ta$_2$Ni(Se$_{1-x}$S$_x$)$_5$

Finite-temperature photoemission in the extended Falicov-Kimball model: a case study for Ta$_2$NiSe$_5$

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