Inelastic light scattering at high-energy excitations in doped cuprate superconductors

Ruebhausen, M.; Rieck, C. T.; Dieckmann, N.; Subke, K.-O.; Böck, Andreas; Merkt, U.

doi:10.1103/physrevb.56.14797

Cited by 52 publications

(56 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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].…”

supporting

confidence: 70%

“…Similarly, it has been known that the ERS detection of twomagnon excitations is assisted by resonant Raman processes [19,20]. For undoped systems, a strong enhancement of the signal is found for incident photon energies in the 2.4-3.0 eV range [8,9,12,21], and it has been common experimental practice to use fixed laser energies suitable for the undoped systems to perform measurements at finite doping [10,11]. A caveat is that the doping dependence of the ERS signal measured in this way may reflect variations not only in the magnetism but also in the resonance condition [8].…”

mentioning

confidence: 99%

See 1 more Smart Citation

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.

View full text Add to dashboard Cite

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...

show abstract

supporting

confidence: 70%

mentioning

confidence: 99%

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.

View full text Add to dashboard Cite

show abstract

“…The superconducting gaps in hole-doped superconductors were investigated by low-energy Raman scattering . Two-magnon excitations and electronic excitations were investigated by wide-energy Raman scattering 72,74,75,77,82,88,94,[97][98][99][100][101][102][103][104][105][106] . Two-magnon scattering is active only in the B 1g spectra 97,98 .…”

Section: Introductionmentioning

confidence: 99%

Superconducting pairing and the pseudogap in the nematic dynamical stripe phase of La_2−xSr_xCuO₄

Sugai

Takayanagi

Hayamizu

et al. 2013

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

The individual k|| and k ⊥ stripe excitations in fluctuating spin-charge stripes have not been observed yet. Raman scattering has a unique selection rule that the combination of two electric field directions of incident and scattered light determines the observed symmetry. If we set, for example, two electric fields to two possible stripe directions, we can observe the fluctuating stripe as if it is static. Using the different symmetry selection rule between the B1g two-magnon scattering and the B1g and B2g isotropic electronic scattering, we succeeded to obtain the k|| and k ⊥ strip magnetic excitations separately in La2−xSrxCuO4. Only the k ⊥ stripe excitations appear in the wide-energy isotropic electronic Raman scattering, indicating that the charge transfer is restricted to the direction perpendicular to the fluctuating stripe. This surprising restriction is reminiscent of the Burgers vector of an edge dislocation in metal. The edge dislocation easily slides perpendicularly to an inserted stripe and causes ductility in metal. Hence charges at the edge of a stripe move together with the edge dislocation perpendicularly to the stripe, while other charges are localized. A looped edge dislocation has lower energy than a single edge dislocation. The superconducting coherence length is close to the inter-charge stripe distance at x ≤ 0.2. Therefore we conclude that Cooper pairs are formed at looped edge dislocations. The restricted charge transfer direction naturally explains the opening of a pseudogap around (0, π) for the stripe parallel to the b axis and the reconstruction of the Fermi surface to have a flat plane near (0, π). They break the four-fold rotational symmetry. Furthermore the systematic experiments revealed the carrier density dependence of the isotropic and anisotropic electronic excitations, the spin density wave and/or charge density wave gap near (π/2, π/2), and the strong coupling between the electronic states near (π/2, π/2) and the zone boundary phonons at (π, π).

show abstract

“…3(a) as a function of Ca concentrations. The spectrum of YBCO exhibits a band peaked at ~ 2900 cm -1 and is assigned to scattering by two-magnon [7]. This peak maximum position shifts upon Ca doping to lower frequency, until it weaken into a very broad peak in x = 0.30 sample.…”

Section: Methodsmentioning

confidence: 99%

Inelastic light scattering studies of overdoped Y_1–xCa_x Ba₂Cu₃O_7–δ thin film

Lin

Weng

Liu³

et al. 2007

Physica Status Solidi (b)

View full text Add to dashboard Cite

The vibrational and magnetic Raman excitation spectra were examined in overdoped Y 1-x Ca x Ba 2 Cu 3 O 7-δ thin films. Below T c , certain phonons in undoped YBa 2 Cu 3 O 7-δ (YBCO) show strong self-energy effects, which gradually vanish with increasing Ca concentration into the overdoped regime. The observed B 1g symmetry two-magnon excitation peak near 2900 cm -1 in YBCO is significantly broadened, weakened, and shifts to the lower frequency with increasing Ca content, indicating the effective value of magnetic superexchange energy decreases and that the life time of the magnons becomes shorter with increasing hole concentrations.

show abstract

Inelastic light scattering at high-energy excitations in doped cuprate superconductors

Cited by 52 publications

References 52 publications

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

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

Superconducting pairing and the pseudogap in the nematic dynamical stripe phase of La_2−xSr_xCuO₄

Inelastic light scattering studies of overdoped Y_1–xCa_x Ba₂Cu₃O_7–δ thin film

Contact Info

Product

Resources

About

Inelastic light scattering at high-energy excitations in doped cuprate superconductors

Cited by 52 publications

References 52 publications

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

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

Superconducting pairing and the pseudogap in the nematic dynamical stripe phase of La2−xSrxCuO4

Inelastic light scattering studies of overdoped Y1–xCax Ba2Cu3O7–δ thin film

Contact Info

Product

Resources

About

Superconducting pairing and the pseudogap in the nematic dynamical stripe phase of La_2−xSr_xCuO₄

Inelastic light scattering studies of overdoped Y_1–xCa_x Ba₂Cu₃O_7–δ thin film