| 1. |
- Nylén, H., et al.
(author)
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O KVV Auger emission versus resonant photoemission at the O K edge of high-Tc superconductors
- 1998
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In: Physica C: Superconductivity and its Applications. - 0921-4534. ; 300:3-4, s. 161-170
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Journal article (peer-reviewed)abstract
- Photoelectron spectroscopy results on single crystals of the superconductors Bi2Sr2CaCu2O8,Bi2Sr 2CuO6, Ba0.6K0.4BiO3 and the semiconductor Ba0.9K0.1BiO3 are reported for the photon energy region around the O K absorption threshold. The development of the O-KVV Auger structure has been carefully monitored as a function of photon energy. A non-monotonic behavior displaying a feature at a constant binding energy of about 14 eV was found for Bi2Sr2CaCu2O8 and Bi2Sr2CuO6 in a narrow photon energy region of 1 eV at the main edge of the O K absorption spectrum around 530 eV. The corresponding enhancement, connected with the autoionization of O 2 p states, is absent in Ba1-xKxBiO3 in contrast to Bi2Sr2CaCu2O8 and Bi2Sr2CuO6. The resonant enhancement is more pronounced for Bi2Sr2CuO6 as compared to Bi2Sr2CaCu2O8, which can be explained by a lower charge carrier concentration in the former case, leading to a more localized nature of intermediate O 2 p states. The model parameters Cu d-d and O p-p Coulomb interactions and the charge transfer energy Δ are estimated from the experiments.
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| 2. |
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| 3. |
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| 4. |
- Tjernberg, O, et al.
(author)
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Evidence of pseudogap related core level shifts in Bi2Sr2Ca1-xYxCu2O8+delta
- 1997
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 79:3, s. 499-502
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Journal article (peer-reviewed)abstract
- Photoelectron spectroscopy data from Bi2Sr2Ca1-xYxCu2O8+delta Single crystals, for x = 0, 0.16, and 0.55, are presented. It is shown that there are core level shifts related to the opening of a pseudogap and that similar shifts are observed at the opening of the superconducting gap in optimally doped samples. This result is in agreement with pair formation above T-c as suggested by V.J. Emery and S.A. Kivelson [Nature (London) 374, 434 (1995)].
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| 5. |
- Tjernberg, O, et al.
(author)
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Evidence of pseudogap related core level shifts in Bi2Sr2Ca1-xYxCu2O8+delta
- 1997
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In: PHYSICAL REVIEW LETTERS. - : AMER INST PHYSICS. - 0031-9007. ; 79:3, s. 499-502
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Journal article (other academic/artistic)abstract
- Photoelectron spectroscopy data from Bi2Sr2Ca1-xYxCu2O8+delta Single crystals, for x = 0, 0.16, and 0.55, are presented. It is shown that there are core level shifts related to the opening of a pseudogap and that similar shifts are observed at the opening
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