Site-selective oxygen isotope effect in optimally doped YBa2Cu3O6 + x

Zech, D.; Keller, H.; Conder, K.; Kaldis, E.; Liarokapis, E.; Poulakis, N.; Müller, K. A.

doi:10.1038/371681a0

Cited by 130 publications

(101 citation statements)

References 24 publications

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“…A small negative OIS [α O = −0.010(4)] associated with the planar oxygen was found. In contrast, Zech et al [35] showed a small positive OIS [α O = 0.018(4)] related to the planar oxygen ions. The above discrepancy may be due to a broad superconducting transition in the samples of Nickel et al [34], which makes it difficult to define T c reliably.…”

Section: Isotope Effect On the Superconducting Transition Temperamentioning

confidence: 92%

“…Although the OIS is small in the optimally-doped samples, the experiment done by Zech et al [35] provided evidence that the planar oxygen ions mainly (80%) contribute to the total OIS (see Fig. 3).…”

Section: Isotope Effect On the Superconducting Transition Temperamentioning

confidence: 97%

“…It is evident that the planar oxygen mainly (> 80%) contributes to the total oxygen-isotope shift in the optimally doped cuprate. After [35].…”

Section: Isotope Effect On the Superconducting Transition Temperamentioning

confidence: 99%

See 2 more Smart Citations

Unconventional isotope effects in the high-temperature cuprate superconductors

Zhao

Keller

Conder

2001

J. Phys.: Condens. Matter

139

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We review various isotope effects in the high-Tc cuprate superconductors to assess the role of the electron-phonon interaction in the basic physics of these materials. Of particular interest are the unconventional isotope effects on the supercarrier mass, on the charge-stripe formation temperature, on the pseudogap formation temperature, on the EPR linewidth, on the spin-glass freezing temperature, and on the antiferromagnetic ordering temperature. The observed unconventional isotope effects strongly suggest that lattice vibrations play an important role in the microscopic pairing mechanism of high-temperature superconductivity.

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Section: Isotope Effect On the Superconducting Transition Temperamentioning

confidence: 92%

Section: Isotope Effect On the Superconducting Transition Temperamentioning

confidence: 97%

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Unconventional isotope effects in the high-temperature cuprate superconductors

Zhao

Keller

Conder

2001

J. Phys.: Condens. Matter

139

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“…5,6 The cuprate high-temperature superconductors (HTS) are characterized by a vanishingly small but positive isotope effect exponent in optimally doped compounds which increases in a monotonic way upon decreasing doping. [7][8][9][10][11][12][13][14] For the optimally doped cuprate HTS the smallest value of the oxygen-isotope exponent α O ≃ 0.02 was obtained for YBa 2 Cu 3 O 7−δ and Bi 2 Sr 2 Ca 2 Cu 3 O 10+δ , while it reaches α O ≃ 0.25 for Bi 2 Sr 1.6 La 0.4 CuO 6+δ . [7][8][9]13,14 In addition, it was demonstrated that in underdoped materials α O exceeds substantially the BCS limit α BCS ≡ 0.5.…”

mentioning

confidence: 98%

“…[7][8][9][10][11][12][13][14] For the optimally doped cuprate HTS the smallest value of the oxygen-isotope exponent α O ≃ 0.02 was obtained for YBa 2 Cu 3 O 7−δ and Bi 2 Sr 2 Ca 2 Cu 3 O 10+δ , while it reaches α O ≃ 0.25 for Bi 2 Sr 1.6 La 0.4 CuO 6+δ . [7][8][9]13,14 In addition, it was demonstrated that in underdoped materials α O exceeds substantially the BCS limit α BCS ≡ 0.5. 8,10,14 It is important to note here that the values of both, the oxygen and the copper isotope exponents in cuprate HTS are always positive.…”

mentioning

confidence: 98%

Intrinsic and structural isotope effects in iron-based superconductors

et al. 2010

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The currently available results of the isotope effect on the superconducting transition temperature Tc in Fe-based high-temperature superconductors (HTSs) are highly controversial. The values of the Fe isotope effect exponent Fe for various families of Fe-based HTS were found to be as well positive, as negative, or even be exceedingly larger than the BCS value BCS 0.5. Here we emphasize that the Fe isotope substitution causes small structural modifications which, in turn, affect Tc. Upon correcting the isotope effect exponent for these structural effects, an almost unique value of 0.35-0.4 is observed for at least three different families of Fe-based HTS.

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Superconductivity in cuprates: Details of electron phonon coupling

Larsson

2009

Int J of Quantum Chemistry

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ABSTRACT:The Bardeen-Cooper-Schrieffer (BCS) model explains superconductivity (SC) as due to correlation between electronic momentum and nuclear momentum (phonons) in a free electron gas. The BCS model lacks chemical specificity, however, since the coupling mechanism is left unspecified. After the discovery of high T C superconductivity in 1986 it was concluded that electron-phonon interactions are insufficient to explain electron pairing. A large part of theoretical research has since been aiming at finding another mechanism that would allow us to consider the superconducting system as a gas of charged free bosons. However, there appears to be no reason to assume free electrons in oxides. In this article the free-electron criterion is therefore replaced by the criterion that a pair of electrons can move freely between sites without resistance, i.e., without activation energy. Electron pair transfer is treated in a many-electron real space approach using standard mixed-valence theories. MottHubbard-U is strictly defined, its dependence on breathing mode coordinates analyzed, and the connection between U and the energy gap for superconductivity clarified. dwave gap anisotropy is found to be consistent with the general atomic level model presented here. Softening of phonon half-breathing modes in inelastic neutron scattering (INS) is connected to mixed-valency. The fundamental vibronic interaction between spin density wave (SDW) and charge density wave (CDW) states leads to a new phase with energy gap and electron pair carriers that can only be the superconducting phase.

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Site-selective oxygen isotope effect in optimally doped YBa2Cu3O6 + x

Cited by 130 publications

References 24 publications

Unconventional isotope effects in the high-temperature cuprate superconductors

Unconventional isotope effects in the high-temperature cuprate superconductors

Intrinsic and structural isotope effects in iron-based superconductors

Superconductivity in cuprates: Details of electron phonon coupling

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