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

M. Karppinen*, Miia Kotiranta, T. Nakane, H. Yamauchi, Sungchun Chang, R.-S. Liu, J. M. Chen

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

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    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 hole concentrations with increasing x are seen as enhancement in the relative intensities of the pre-edge peaks at ∼528.3 and ∼530.5 eV, respectively.

    Original languageEnglish
    Article number134522
    Pages (from-to)1-6
    Number of pages6
    JournalPhysical Review B
    Issue number13
    Publication statusPublished - Apr 2003
    MoE publication typeA1 Journal article-refereed


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