X-ray absorption of Ba1 − xKxBiO3 and BaPb1 − yBiyO3: Competition between bipolaronic and charge-density wave states

Bulk-sensitive O 1s near-edge X-ray absorption spectroscopy on Ba1 - xKxBiO3 and BaPb1 - yBiyO3 single crystals shows for undoped BaBiO3 a distinct charge-density wave derived band slightly above the Fermi level; upon K doping it is effectively reduced and competes with bipolaronic hole states whose...

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Bibliographic Details
Published in:Europhysics letters 2005-10, Vol.72 (2), p.275-281
Main Authors: Merz, M, Nücker, N, Schuppler, S, Arena, D, Dvorak, J, Idzerda, Y. U, Ustinovich, S. N, Soldatov, A. G, Shiryaev, S. V, Barilo, S. N
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Language:English
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Summary:Bulk-sensitive O 1s near-edge X-ray absorption spectroscopy on Ba1 - xKxBiO3 and BaPb1 - yBiyO3 single crystals shows for undoped BaBiO3 a distinct charge-density wave derived band slightly above the Fermi level; upon K doping it is effectively reduced and competes with bipolaronic hole states whose spectral weight increases with K content. For Pb doping, on the other hand, a wide Pb-O band is formed near EF while the intensity of the bipolaronic hole band remains unaffected. The data suggest a crucial role of hole bipolarons for bismuthate superconductivity.
ISSN:0295-5075
1286-4854
DOI:10.1209/epl/i2005-10236-6