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

Article

关键词: X-RAY-ABSORPTION;    T-C;    SUPERCONDUCTING PROPERTIES;    OXYGEN-CONTENT;    DENSITY;    BI2SR2(CA1-XYX)CU2O8+DELTA;    BI2SR2CA1-XYXCU2O8+DELTA;    YBA2CU3O7-DELTA;    SUBSTITUTION;    BISMUTH;   

DOI  :  10.1103/PhysRevB.67.134522

来源: SCIE

【 摘 要 】

Induction of holes not only in the superconductive CuO2 plane but also in the Bi2O2+delta charge reservoir of the Bi2Sr2(Y1-xCax)Cu2O8+delta superconductor upon Ca-II-for-Y-III 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 L-2,L-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+delta/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 T-c is obtained at the hole concentration of 0.12. In the O K-edge XANES spectrum, the increases in the CuO2-plane and BiO1+delta/2-layer hole concentrations with increasing x are seen as enhancement in the relative intensities of the pre-edge peaks at similar to528.3 and similar to530.5 eV, respectively.

【 授权许可】

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