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Falck, J. P.; Levy, A.; Kastner, M. A.; Birgeneau, R. J.

doi:10.1103/physrevlett.69.1109

Cited by 120 publications

(87 citation statements)

References 16 publications

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“…The CT peak (CTP) in s 1 (o) is at B2.3 eV, while the gap, estimated from a simple linear interpolation (red dashed line in Fig. 1), is at about D ¼ 1.8 eV for T ¼ 130 K and is consistent with previous reports [6][7][8][9]26 . The non-vanishing optical conductivity below the gap is due to the presence of tail states.…”

Section: Resultssupporting

confidence: 78%

Witnessing the formation and relaxation of dressed quasi-particles in a strongly correlated electron system

et al. 2014

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The non-equilibrium approach to correlated electron systems is often based on the paradigm that different degrees of freedom interact on different timescales. In this context, photo-excitation is treated as an impulsive injection of electronic energy that is transferred to other degrees of freedom only at later times. Here, by studying the ultrafast dynamics of quasi-particles in an archetypal strongly correlated charge-transfer insulator (La 2 CuO 4 þ d ), we show that the interaction between electrons and bosons manifests itself directly in the photo-excitation processes of a correlated material. With the aid of a general theoretical framework (Hubbard-Holstein Hamiltonian), we reveal that sub-gap excitation pilots the formation of itinerant quasi-particles, which are suddenly dressed by an ultrafast reaction of the bosonic field.

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Section: Resultssupporting

confidence: 78%

Witnessing the formation and relaxation of dressed quasi-particles in a strongly correlated electron system

et al. 2014

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“…However, this is not without controversy; Falck and coworkers have argued that the sharp feature in the optical data arises from the shortrange interaction between an unbound electron and hole pair created by the CT process [16,19]. The present data, and in particular the q-dependence of Fig.…”

supporting

confidence: 46%

Resonant Inelastic X-Ray Scattering Study of Charge Excitations inLa2CuO4

Kim

Hill

Burns³

et al. 2002

Phys. Rev. Lett.

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112

102

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We report a resonant inelastic x-ray scattering study of the dispersion relations of charge transfer excitations in insulating La2CuO4. These data reveal two peaks, both of which show two-dimensional characteristics. The lowest energy excitation has a gap energy of ∼ 2.2 eV at the zone center, and a dispersion of ∼ 1 eV. The spectral weight of this mode becomes dramatically smaller around (π, π). The second peak shows a smaller dispersion (∼ 0.5 eV) with a zone-center energy of ∼ 3.9 eV. We argue that these are both highly dispersive exciton modes damped by the presence of the electron-hole continuum.PACS numbers: 74.25.Jb, 74.72.Dn, 78.70.Ck, Understanding strongly correlated electron systems, such as the cuprate superconductors, remains at the heart of much of current condensed matter research. As a first step toward elucidating electron correlation effects in these systems, it is important to study the behavior of elementary excitations using various spectroscopic tools. For example, angle resolved photoemission spectroscopy (ARPES) has become an indispensable probe for studying the excitation spectrum of a single quasiparticle [1,2], while inelastic neutron scattering has been invaluable in the investigation of low-energy collective modes (1 ∼ 100 meV), such as phonons and magnons [3]. However, to date only limited information has been available on collective excitations at an energy scale on the order of ∼ 1 eV. This is unfortunate, since in this energy range, the electron dynamics are governed directly by the various hopping integrals and by the Coulomb interaction. Thus, an investigation of the dispersion relations of such collective charge excitations would yield invaluable information for any microscopic theory of charge dynamics in the copper oxides.In this Letter, we present a detailed study of the momentum-dependence of the charge excitations in La 2 CuO 4 , utilizing resonant inelastic x-ray scattering (RIXS). In the simplest picture of this insulating cuprate, the ground state consists of one hole per copper ion (Cu 2+ ), and the low-lying electronic excitations include excitons formed via a charge-transfer (CT) process, in which charge is moved from the oxygen onto the copper [4,5,6]. Specifically, an electron-hole pair, created by exciting an electron from the valence band -the ZhangRice (ZR) band [7] -to the conduction band across the CT gap, can form a bound exciton state as a result of the Coulomb interaction. This CT exciton is expected to have a large dispersion, since it has zero spin and can move without disturbing the antiferromagnetic order of the copper oxide plane. Consistent with this, our highresolution measurements have enabled us to identify an exciton-like feature at 2.2 eV with a dispersion of 1 eV. In addition, a second peak at slightly higher energy is also observed. This has a zone-center energy of 3.9 eV and a dispersion of 0.5 eV. Finally, we also discuss a dramatic reduction in spectral weight of the CT exciton observed near the (π π) position.The RIXS technique in the hard...

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“…The narrowness of the charge transfer peak was attributed to the electron-hole interaction, i.e., excitonic effect, which can dramatically enhance matrix elements for interband transition in two-dimensional system. 27 As temperature increased, the charge transfer peak became broader and shifted to lower energy. At the low temperatures below 100 K, the peak energy did not show discernible change and it decreased continuously with increasing temperature above 100 K. These temperature-induced changes in ͑ ͒ were explained in terms of the coupling of charge carriers to a optical phonon mode, i.e., electronphonon coupling.…”

Section: Comparison With Optical Spectra Of La 2 Cuo 4 : Excitonicmentioning

confidence: 99%

Temperature dependence of the electronic structure of theJeff=12Mott insulator
Moon
¹
,
Jin
²
,
Choi
³

et al. 2009
Phys. Rev. B
157
25
100
5
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We investigated the temperature-dependent evolution of the electronic structure of the J eff = 1 2 Mott insulator Sr 2 IrO 4 using optical spectroscopy. The optical conductivity spectra ͑ ͒ of this compound has recently been found to exhibit two d-d transitions associated with the transition between the J eff = 1 2 and J eff = 3 2 bands due to the cooperation of the electron correlation and spin-orbit coupling. As the temperature increases, the two peaks show significant changes resulting in a decrease in the Mott gap. The experimental observations are compared with the results of first-principles calculation in consideration of increasing bandwidth. We discuss the effect of the temperature change in the electronic structure of Sr 2 IrO 4 in terms of local lattice distortion, excitonic effect, electron-phonon coupling, and magnetic ordering.

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Charge-transfer spectrum and its temperature dependence inLa2CuO4

Cited by 120 publications

References 16 publications

Witnessing the formation and relaxation of dressed quasi-particles in a strongly correlated electron system

Witnessing the formation and relaxation of dressed quasi-particles in a strongly correlated electron system

Resonant Inelastic X-Ray Scattering Study of Charge Excitations inLa2CuO4

Temperature dependence of the electronic structure of theJeff=12Mott insulator
Moon
¹
,
Jin
²
,
Choi
³

et al. 2009
Phys. Rev. B
157
25
100
5
View full text Add to dashboard Cite

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Charge-transfer spectrum and its temperature dependence inLa2CuO4

Cited by 120 publications

References 16 publications

Witnessing the formation and relaxation of dressed quasi-particles in a strongly correlated electron system

Witnessing the formation and relaxation of dressed quasi-particles in a strongly correlated electron system

Resonant Inelastic X-Ray Scattering Study of Charge Excitations inLa2CuO4

Temperature dependence of the electronic structure of theJeff=12Mott insulatorMoon1, Jin2, Choi3 et al. 2009Phys. Rev. B157251005View full textAdd to dashboardCite

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Temperature dependence of the electronic structure of theJeff=12Mott insulator
Moon
¹
,
Jin
²
,
Choi
³

et al. 2009
Phys. Rev. B
157
25
100
5
View full text Add to dashboard Cite