X-ray absorption of $\chem{Ba_{1- \it x}K_{\it x}BiO_{3}}$and $\chem{BaPb_{1-\it y}Bi_{\it y}O_{3}}$: Competition between bipolaronic and charge-density wave states

Bulk-sensitive O $1s$ near-edge X-ray absorption spectroscopy on $\chem{Ba_{1-{\it x}}K_{\it x}BiO_{3}}$ and $\chem{BaPb_{1-{\it y}}Bi_{\it y} O_{3}}$ single crystals shows for undoped $\chem{BaBiO_{3}}$ a distinct charge-density wave derived band slightly above the Fermi level; upon K doping it is...

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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.
Format: Article
Language:English
Subjects:
74.20.Mn
74.25.Jb
78.70.Dm
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Summary:Bulk-sensitive O $1s$ near-edge X-ray absorption spectroscopy on $\chem{Ba_{1-{\it x}}K_{\it x}BiO_{3}}$ and $\chem{BaPb_{1-{\it y}}Bi_{\it y} O_{3}}$ single crystals shows for undoped $\chem{BaBiO_{3}}$ 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