Polarized reflectance spectra of a (001) surface of YBa2Cu3O7 before and after detwinning

Zibold, A.; Dürrler, M.; Geserich, H. P.; Erb, A.; Müller‐Vogt, G.

doi:10.1016/0921-4534(90)90468-t

Cited by 36 publications

(9 citation statements)

References 9 publications

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“…These correspond to the so-called plane and chain contributions to the optical properties of the material. 50,51 The existence of two in-plane plasma frequencies, which is difficult to measure in unpolarized reflectance spectroscopy, is clearly evident in the TDR spectrum of YBCO.…”

Section: B Normal-state Thermal-difference Reflectance Spectra Of Cumentioning

confidence: 99%

“…[43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59] Often, these measurements extend well into the superconducting state, and in general, these measurements concentrate on the existence of the optical gap edge, 2⌬ 0 (T), even though it is well known that it is the small variations in the optical properties of a superconductor at energies well above 2⌬ 0 (T) that contain information on the nature of the pairing interaction.…”

Section: Introductionmentioning

confidence: 99%

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Thermal-difference reflectance spectroscopy of the high-temperature cuprate superconductors

et al. 1996

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have been measured for photon energies between 0.3 and 4.5 eV at temperatures above and below each material's superconducting critical temperature. The amplitude of the characteristic optical structure near the screened plasma frequency of each sample in the normal-state TDR spectrum varies approximately linearly with temperature, T, indicating that the temperature-dependent optical scattering rate in these materials scales with temperature as T 2 . From the TDR spectra collected above and below the critical temperature of each sample, the superconducting to normal-state reflectance ratio, R S /R N , has been obtained. In all of these spectra, there are significant deviations from unity in R S /R N at photon energies on the order of 2.0 eV. This optical structure cannot be accounted for using the conventional Mattis-Bardeen description of the optical properties of a superconductor or its strong-coupling extension where electron-pairing interactions are limited to energies less than 0.1 eV. However, both the temperature and energy dependence of the structure in the R S /R N spectra may be adequately described within Eliashberg theory with an electron-boson coupling function which consists of both a low-energy component ͑Ͻ0.1 eV͒ and a high-energy component located between 1.6 and 2.1 eV.

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Section: B Normal-state Thermal-difference Reflectance Spectra Of Cumentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermal-difference reflectance spectroscopy of the high-temperature cuprate superconductors

et al. 1996

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“…Section IV discusses the implications of the NEXAFS results and, finally, the conclusions are drawn in Sec. V. 41,42,44 Well-reflecting flat ͑001͒ surfaces of the samples were obtained by cutting off the crystals' top layers using the diamond knife of an ultramicrotome.…”

Section: Introductionmentioning

confidence: 99%

X-ray absorption spectroscopy of detwinnedPrxY1−

et al. 1997

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UvA-DARE is a service provided by the library of the University of Amsterdam (http://dare.uva.nl) UvA-DARE (Digital Academic Repository)X-ray absorption spectroscopy of detwinned PrxY1-xBa2Cu3O7-y single crystals: electronic structure and hole distribution Merz, M.; Nücker, N.; Pellegrin, E.; Schweiss, P.; Schuppler, S.; Kielwein, M.; Knupfer, M.; Golden, M.S.; Fink, J. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Substituting Y in orthorhombic ͑Y,R)Ba 2 Cu 3 O 7 by any rare-earth element R has generally little effect on the superconducting properties. For RϭPr, however, superconductivity is completely suppressed. To understand this effect we have studied the unoccupied electronic structure of Pr x Y 1Ϫx Ba 2 Cu 3 O 7Ϫy (xϭ0.0, 0.4, 0.8) using polarization-dependent O 1s near-edge x-ray absorption spectroscopy of detwinned single crystals. We identify the hole states in the CuO 2 planes and the CuO 3 chains and give estimates of the relative contributions of the O 2p x , O 2p y , and O 2p z orbitals to these states. Along with the comparison of oxygen-rich (yϷ0.1) to the oxygen-depleted materials (yϷ0.9), this allows a test of the current theoretical explanations for the Pr-induced suppression of superconductivity. While we can rule out models involving hole filling or charge transfer between the planes and the chains, our data are consistent with approaches based on Pr 4f -O 2p hybridization. ͓S0163-1829͑97͒03313-4͔

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“…2. The enthalpies and entropies of reactions (22) and (23) are calculated by using the partial molar enthalpy of oxygen in the 123 (from Ref. 25) and the oxidation entropy of the 123 (from Ref.…”

Section: Phase Equilibrium Between the 123 And 247 Phasesmentioning

confidence: 99%

“…4 The lattice parameters, a, b, and c of the 247 phase vary with oxygen stoichiometry, y, showing trends similar to those of the 123 phase. 6,22 However, the 247 structure does not transform to a tetragonal structure even at the lowest oxygen stoichiometry, y ∼ 14.0. 6 As oxygen stoichiometry increases, oxygen can take sites on the a axis in the 247 cell.…”

Section: Introductionmentioning

confidence: 97%

Phase equilibria among the superconductors in the Y₂O₃–BaO–Cu–O system

Zhou

Navrotsky

1999

J. Mater. Res.

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The enthalpy of formation of Y 2 Ba 4 Cu 7 O 14.864 at room temperature has been determined by using high-temperature reaction calorimetry. The standard enthalpy of formation of the 247 phase is ⌬H°f ‫ס‬ −5463 ± 18 kJ mol −1 . Phase relationships among the superconductors, namely, the 123, 124, and 247, are assessed. It is intrinsic that impurity phases, such as Y 2 Cu 2 O 5 , BaCuO 2 , CuO, etc., coexist with the superconductors at equilibrium. Equilibria among the superconductor phases in the Y 2 O 3 -BaO-Cu-O system have been determined. The results show that, at the 124 bulk composition, the 247 phase coexists with the excess CuO in a narrow area of p O 2 ∼ T space confined by the stability fields of the 124 phase and a mixture of the 123 + CuO. The standard free energies of carbonation and hydration of the 247 phase are also determined, which are −629 ± 13 kJ mol −1 and −873 ± 45 kJ mol −1 , respectively. Like the 123 and 124 phases, the 247 phase is thermodynamically unstable for corrosion by water vapor and carbon dioxide in ambient atmosphere.

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Polarized reflectance spectra of a (001) surface of YBa2Cu3O7 before and after detwinning

Cited by 36 publications

References 9 publications

Thermal-difference reflectance spectroscopy of the high-temperature cuprate superconductors

Thermal-difference reflectance spectroscopy of the high-temperature cuprate superconductors

X-ray absorption spectroscopy of detwinnedPrxY1−

Phase equilibria among the superconductors in the Y₂O₃–BaO–Cu–O system

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Polarized reflectance spectra of a (001) surface of YBa2Cu3O7 before and after detwinning

Cited by 36 publications

References 9 publications

Thermal-difference reflectance spectroscopy of the high-temperature cuprate superconductors

Thermal-difference reflectance spectroscopy of the high-temperature cuprate superconductors

X-ray absorption spectroscopy of detwinnedPrxY1−

Phase equilibria among the superconductors in the Y2O3–BaO–Cu–O system

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Phase equilibria among the superconductors in the Y₂O₃–BaO–Cu–O system