Layer-specific hole concentrations in Bi2Sr2(Y1-xCax) Cu2O8+δ as probed by XANES spectroscopy and coulometric redox analysis

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Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2003-04
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Language
en
Pages
6
1-6
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PHYSICAL REVIEW B, Volume 67, issue 13
Abstract
Induction of holes not only in the superconductive CuO2 plane but also in the Bi2O2-δ charge reservoir of the Bi2Sr2(Y1-xCax) Cu2O8+δ superconductor upon CaII-for-YIII substitution is evidenced by means of two independent techniques, i.e., high-resolution x-ray-absorption near-edge structure (XANES) spectroscopy measurements and coulometric redox titrations. The absolute values derived for the CuO2-plane hole concentration from the Cu L2,3-edge XANES spectra are in good agreement with those obtained from the coulometric redox analysis. The CuO2-plane hole concentration is found to increase from 0.03 to 0.14 concomitantly with the increase in the BiO1+δ/2-layer hole concentration from 0.00 to 0.13 as the Ca-substitution level, x, increases from 0 to 1. The threshold CuO2-plane hole concentration for the appearance of superconductivity is determined at 0.06, while the highest Tc is obtained at the hole concentration of 0.12. In the O K-edge XANES spectrum, the increases in the CuO2-plane and BiO1+δ/2-layer holeconcentrations with increasing x are seen as enhancement in the relative intensities of the pre-edge peaks at ∼528.3 and ∼530.5 eV, respectively.
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Karppinen , M , Kotiranta , M , Nakane , T , Yamauchi , H , Chang , S , Liu , R-S & Chen , J M 2003 , ' Layer-specific hole concentrations in Bi 2 Sr 2 (Y 1-x Ca x ) Cu 2 O 8+δ as probed by XANES spectroscopy and coulometric redox analysis ' , Physical Review B , vol. 67 , no. 13 , 134522 , pp. 1-6 . https://doi.org/10.1103/PhysRevB.67.134522