Layer-specific hole concentrations in Bi2Sr2(Y1-xCax) Cu2O8+δ as probed by XANES spectroscopy and coulometric redox analysis
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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en
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6
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Physical Review B, Volume 67, issue 13, pp. 1-6
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 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.Description
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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