Electronic structure of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">CuGeO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mo>:</mml:mo></mml:math>Charge excitations between zero and one dimension

Atzkern, S.; Knupfer, M.; Golden, M. S.; Fink, J.; Hübsch, A.; Waidacher, C.; Becker, K. W.; Linden, Wolfgang von der; Weiden, M.; Geibel, C.

doi:10.1103/physrevb.64.075112

Cited by 16 publications

(19 citation statements)

References 32 publications

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“…A similar structure, followed at high photon energies by a region of strong absorption ascribed to transitions to the empty states above the charge transfer gap, is also present in transmission EELS spectra, 10 in the optical spectra, 11 and in x-ray Raman scattering spectra. 12 The energy position and the strong dependence of this peak on light polarization suggest that this structure can be related to the Zhang-Rice-like exciton.…”

mentioning

confidence: 56%

“…Due to the hybridization between Cu 3d and O 2p orbitals and to the strong dependence of the charge transfer excitation on the geometry of the Cu-O plaquettes, the picture of charge transfer excitation alone can not fully account for the fine structure details of the observed spectrum. Indeed, as pointed out by Zhang and Ng 15 and, successively, by Atzkern et al, 10 depending on Cu-O hybridization and bond geometry, the CT excitation picture should be completed by an analysis of the hole delocalization. Zhang and Ng 15 describe the CT-exciton in the insulating CuO2 plane and conclude that a very complex exciton is formed, consisting of a 3d electron on copper and a nearby Cu-O singlet.…”

mentioning

confidence: 96%

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Role of the Zhang-Rice-like exciton in optical absorption spectra ofCuGeO3andCuGe1−
Pagliara
¹
,
Parmigiani
²
,
Galinetto
³

et al. 2002
Phys. Rev. B
17
1
13
0
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The optical excitations in pure and Si-substituted CuGeO 3 are investigated in the 15-300 K temperature range. A structure, detected for the E field parallel to the c axis of the crystals at about 3.2 eV, is due to the formation of a Zhang-Rice-like ͑ZR͒ exciton. The weak oscillator strength is due to the low mobility of the ZR-like exciton between the edge-sharing CuO 4 plaquettes of CuGeO 3 . The temperature dependence of the ZR-like energy is explained by a renormalization effect involving phonon-electron interactions or changes in spin ordering, while the increase of ZR-like exciton intensity with the Si content is argued to arise from a different hybridization of the Si-O bond with respect to Ge-O.

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mentioning

confidence: 56%

mentioning

confidence: 96%

Role of the Zhang-Rice-like exciton in optical absorption spectra ofCuGeO3andCuGe1−
Pagliara
¹
,
Parmigiani
²
,
Galinetto
³

et al. 2002
Phys. Rev. B
17
1
13
0
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“…In particular, we obtain n ph /n Cu ≈Φ pump α/n Cu ≃0.1-0.2%, being α=500 cm −1 . Considering the rapid delocalization of each hole within about 5 neighboring plaquettes, 13 it is possible to conclude that, during the pulse duration, ∼0.5-1% of the Cu−O 6 units are driven to the excited state where the correlated 3d bands are locally filled by an electron and a hole is shared among the O-2p orbitals and the Cu-3d levels of the neighboring plaquettes (see Fig. 1d), possibly altering both the interaction U and the transfer integral T pd , and leaving the system in a metastable non-thermal phase.…”

Section: Resultsmentioning

confidence: 99%

“…The shoulder in the absorption coefficient at 3.1-3-2 eV (see Fig. 1c) is attributed to a superposition of plasmons related to transitions from the ground state, being 72% of the hole density localized on Cu atoms, into a delocalized final state with a high occupation probability of the neighbor plaquettes, 13,15 as shown in Fig. 1d.…”

Section: 18mentioning

confidence: 99%

Disentangling thermal and nonthermal excited states in a charge-transfer insulator by time- and frequency-resolved pump-probe spectroscopy

et al. 2009

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Time-and-frequency resolved pump-probe optical spectroscopy is used to investigate the effect of the impulsive injection of delocalized excitations through a charge-transfer process in insulating CuGeO3. A large broadening of the charge-transfer edge is observed on the sub-ps timescale. The modification of this spectral feature can not be attributed to the local increase of the effective temperature, as a consequence of the energy absorbed by the pump pulse. The measured modifications of the optical properties of the system are consistent with the creation of a non-thermal state, metastable on the ps timescale, after the pump-induced impulsive modification of the electron interactions.

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“…For quasi-one dimensional compounds a large values of ε ∞ ∼ 8 was taken in Refs. 19,20. This means that the rest of the solid strongly screens the long-range part of the Coulomb interaction between electrons that enter the Hubbard model.…”

Section: Resultsmentioning

confidence: 99%

Dispersion of the dielectric function of a charge-transfer insulator

2003

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We study the problem of dielectric response in the strong coupling regime of a charge transfer insulator. The frequency and wave number dependence of the dielectric function ε(q, ω) and its inverse ε −1 (q, ω) is the main object of consideration. We show that the problem, in general, cannot be reduced to a calculation within the Hubbard model, which takes into account only a restricted number of electronic states near the Fermi energy. The contribution of the rest of the system to the longitudinal response (i.e. to ε −1 (q, ω)) is essential for the whole frequency range. With the use of the spectral representation of the two-particle Green's function we show that the problem may be divided into two parts: into the contributions of the weakly correlated and the Hubbard subsystems. For the latter we propose an approach that starts from the correlated paramagnetic ground state with strong antiferromagnetic fluctuations. We obtain a set of coupled equations of motion for the two-particle Green's function that may be solved by means of the projection technique. The solution is expressed by a two particle basis that includes the excitonic states with electron and hole separated at various distances. We apply our method to the multiband Hubbard (Emery) model that describes layered cuprates. We show that strongly dispersive branches exist in the excitonic spectrum of the 'minimal' Emery model (1/U d = U p = t pp = 0) and consider the dependence of the spectrum on finite oxygen hopping t pp and on-site repulsion U p . The relationship of our calculations to electron energy loss spectroscopy is discussed.

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Electronic structure ofCuGeO3:Charge excitations between zero and one dimension

Cited by 16 publications

References 32 publications

Role of the Zhang-Rice-like exciton in optical absorption spectra ofCuGeO3andCuGe1−
Pagliara
¹
,
Parmigiani
²
,
Galinetto
³

et al. 2002
Phys. Rev. B
17
1
13
0
View full text Add to dashboard Cite

Role of the Zhang-Rice-like exciton in optical absorption spectra ofCuGeO3andCuGe1−
Pagliara
¹
,
Parmigiani
²
,
Galinetto
³

et al. 2002
Phys. Rev. B
17
1
13
0
View full text Add to dashboard Cite

Disentangling thermal and nonthermal excited states in a charge-transfer insulator by time- and frequency-resolved pump-probe spectroscopy

Dispersion of the dielectric function of a charge-transfer insulator

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Electronic structure ofCuGeO3:Charge excitations between zero and one dimension

Cited by 16 publications

References 32 publications

Role of the Zhang-Rice-like exciton in optical absorption spectra ofCuGeO3andCuGe1−Pagliara1, Parmigiani2, Galinetto3 et al. 2002Phys. Rev. B171130View full textAdd to dashboardCite

Role of the Zhang-Rice-like exciton in optical absorption spectra ofCuGeO3andCuGe1−Pagliara1, Parmigiani2, Galinetto3 et al. 2002Phys. Rev. B171130View full textAdd to dashboardCite

Disentangling thermal and nonthermal excited states in a charge-transfer insulator by time- and frequency-resolved pump-probe spectroscopy

Dispersion of the dielectric function of a charge-transfer insulator

Contact Info

Product

Resources

About

Role of the Zhang-Rice-like exciton in optical absorption spectra ofCuGeO3andCuGe1−
Pagliara
¹
,
Parmigiani
²
,
Galinetto
³

et al. 2002
Phys. Rev. B
17
1
13
0
View full text Add to dashboard Cite

Role of the Zhang-Rice-like exciton in optical absorption spectra ofCuGeO3andCuGe1−
Pagliara
¹
,
Parmigiani
²
,
Galinetto
³

et al. 2002
Phys. Rev. B
17
1
13
0
View full text Add to dashboard Cite