Resonant two‐magnon Raman scattering in high‐<i>T</i><sub>c</sub> cuprates

Kupčić, Ivan

doi:10.1002/jrs.2792

Cited by 3 publications

(4 citation statements)

References 39 publications

(117 reference statements)

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“…Here, δt ν (q) = (g ν / √ N)u νq is the product of the phonon field u νq and the electron-phonon coupling constant g ν / √ N (e ν q is the related polarization vector, and u a νq = −u b νq ≡ u νq ). [5,19] Furthermore,…”

Section: Adiabatic Approximationmentioning

confidence: 99%

“…(Refs [2,5]) and Eqn (1) for the interband optical conductivity, we obtain four contributions to the photon-two-phonon coupling function T νν,αα (ω i ), corresponding to four terms in the factor…”

Section: Adiabatic Approximationmentioning

confidence: 99%

“…The Emery threeband model for cuprate superconductors is the typical example where this happens for usual laser energies. [5] …”

Section: Asymmetry Of Band Dispersionsmentioning

confidence: 99%

“…These effects are explained within a multiband electronic model with relatively complicated band dispersions by treating the doubleresonant (DR) and triple-resonant (TR) scattering processes on equal footing. [4,5] A closely related effect is the laser energy dependence of the position of the disorder-induced D band and the corresponding second-order G band in different sp 2 -based carbon materials. [6 -12] Physical grounds for the dispersive behavior of these two Raman signals in graphite have been explained by Thomsen and Reich (Ref.…”

Section: Introductionmentioning

confidence: 99%

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Triple‐resonant two‐phonon Raman scattering in graphene

Kupčić¹

2011

J Raman Spectroscopy

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The triple-resonant (TR) second-order Raman scattering mechanism in graphene is re-examined. It is shown that the magnitude of the TR contribution to the photon-G mode coupling function in graphene is one order of magnitude larger than the widely accepted two-resonant coupling. Enhancement of the order of 100 in the Raman intensity, with respect to the usual double-resonant model, is found for the G band in graphene, and is expected in the related sp 2 -based carbon materials, as well.

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Section: Adiabatic Approximationmentioning

confidence: 99%

Section: Adiabatic Approximationmentioning

confidence: 99%

“…The Emery threeband model for cuprate superconductors is the typical example where this happens for usual laser energies. [5] …”

Section: Asymmetry Of Band Dispersionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Triple‐resonant two‐phonon Raman scattering in graphene

Kupčić¹

2011

J Raman Spectroscopy

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Recent advances in linear and nonlinear Raman spectroscopy. Part VI

Nafie

2012

J Raman Spectroscopy

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The purpose of this review is to provide a concise overview of recent advances in the broadly defined field of Raman spectroscopy as reflected in part by the many articles published each year in Journal of Raman Spectroscopy as well as in trends across all related journals publishing in this research area. Context for this review is derived from statistical data on article counts obtained from Thomson Reuters ISI Web of Knowledge by year and by subfield of Raman spectroscopy. Additional information is gleaned from presentations featuring Raman spectroscopy presented at the XXIII International Conference on Raman Spectroscopy in Bangalore, India, in August 2012 and at Scientific Exchange 2012 sponsored by the Federation of Analytical Chemistry and Spectroscopy Societies in Kansas City, Missouri, USA, October 2012. Papers published in the Journal of Raman Spectroscopy in 2011 are highlighted in this review and reflect trends at the cutting edge of Raman spectroscopy, a field that is expanding rapidly as a sensitive photonic probe of matter at the molecular level with an ever widening sphere of novel applications. Copyright © 2012 John Wiley & Sons, Ltd.

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Doping-Dependent Photon Scattering Resonance in the Model High-Temperature SuperconductorHgBa2CuO4+δRevealed by Raman Scattering and Optical Ellipsometry

Tacon

Matiks

et al. 2013

Phys. Rev. Lett.

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We study the model high-temperature superconductor HgBa2CuO 4+δ with electronic Raman scattering and optical ellipsometry over a wide doping range. The resonant Raman condition which enhances the scattering cross section of "two-magnon" excitations is found to change strongly with doping, and it corresponds to a rearrangement of inter-band optical transitions in the 1-3 eV range seen by ellipsometry. This unexpected change of the resonance condition allows us to reconcile the apparent discrepancy between Raman and x-ray detection of magnetic fluctuations in superconducting cuprates. Intriguingly, the strongest variation occurs across the doping level where the antinodal superconducting gap reaches its maximum.PACS numbers: 74.25.nd, 74.72.Gh, 74.72.Kf Magnetic fluctuations might play an essential role in the mechanism of high-temperature superconductivity in the cuprates [1]. Upon doping the insulating parent compounds, the fluctuations evolve from antiferromagnetic (AF) magnon excitations up to a few hundred meV. As this energy is in principle sufficient to support superconductivity at very high temperatures, the observation of similar "paramagnon" excitations by resonant inelastic x-ray scattering (RIXS) in superconducting cuprates [2] is a revealing result. Recent electronic Raman scattering (ERS) measurements further suggest that the high-energy magnetic fluctuations exhibit a pronounced change concurrent with the formation of Cooper pairs [3], corroborating a close connection between them.Here we address a major puzzle that has arisen from the comparison of the doping dependent RIXS and ERS cross sections. Both techniques use inelastic photon scattering to probe fundamental excitations in solids, but with very different incident photon energies in the xray and visible-light range, and they can detect magnetic fluctuations in the cuprates via the creation of single- [4] and two-magnon [5] excitations, respectively. In the undoped AF insulating compounds, the superexchange energies J determined by RIXS and ERS agree reasonably well [4,5] and are furthermore consistent with inelastic neutron scattering (INS) measurements [6]. A comparison between these measurements at finite doping, however, reveals an important discrepancy: while the energy and spectral weight of the (para)magnon excitations observed by RIXS exhibit little change [2,7], both of these quantities decrease substantially in ERS data [8][9][10][11]. The latter observation has created the impression that the AF spin fluctuations become overdamped near and above optimal doping [9]. This, in turn, has served as a major argument against magnetically driven Cooper pairing in the overdoped regime [12,13]. Together with the decrease of well-defined high-energy magnetic signal with doping in INS measurements [14], this has cast doubt on the interpretation of the RIXS results [15].The RIXS cross section in the cuprates is known to exhibit a non-trivial photon energy dependence [16,17], and the detection of magnetic excitations is greatly enhanced by a r...

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Resonant two‐magnon Raman scattering in high‐T_c cuprates

Cited by 3 publications

References 39 publications

Triple‐resonant two‐phonon Raman scattering in graphene

Triple‐resonant two‐phonon Raman scattering in graphene

Recent advances in linear and nonlinear Raman spectroscopy. Part VI

Doping-Dependent Photon Scattering Resonance in the Model High-Temperature SuperconductorHgBa2CuO4+δRevealed by Raman Scattering and Optical Ellipsometry

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Resonant two‐magnon Raman scattering in high‐Tc cuprates

Cited by 3 publications

References 39 publications

Triple‐resonant two‐phonon Raman scattering in graphene

Triple‐resonant two‐phonon Raman scattering in graphene

Recent advances in linear and nonlinear Raman spectroscopy. Part VI

Doping-Dependent Photon Scattering Resonance in the Model High-Temperature SuperconductorHgBa2CuO4+δRevealed by Raman Scattering and Optical Ellipsometry

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Resonant two‐magnon Raman scattering in high‐T_c cuprates