XANES Study on the Generation and Distribution of Holes via Ca Substitution and O Doping in Cu(Ba0.8Sr0.2)2(Yb1−Ca )Cu2O6+

Layer-specific hole concentrations inBi2Sr2(Y

“…Before the fitting the spectra are first normalized to have the same spectral weight in the energy range of 535 to 555 eV, and then multiplied by the exact oxygen content of the sample as determined by wet-chemical analysis. 17 The latter operation is not …”

“…Before the fitting the spectra are first normalized to have the same spectral weight in the energy range of 535 to 555 eV, and then multiplied by the exact oxygen content of the sample as determined by wet-chemical analysis. 17 The latter operation is not highly meaningful but rather theoretical as it affects the final results less than 3 %. In peaks, suggesting that the valences of Cu and Bi increase with quite similar rates with increasing Ca substitution level.…”

Oxygen nonstoichiometry and valence of copper in the Cu-1222 superconductor

“…(In the case of the HPO samples, O K-edge data were not considered due to Ag oxide inclusions in these samples in not welldefined amounts.) The pre-edge peak seen for all the samples about $528.1 eV is the well-known signature of hole states in the p-type doped CuO 2 planes in high-T c superconductors [20,[25][26][27][28]31,[34][35][36]. We can distinguish another pre-edge peak at $527.3 eV partly overlapping with this peak.…”

“…At the same time, no sign of an additional peak around 934 eV is seen that would indicate the presence of (two-fold coordinated) monovalent Cu species. (Note that such a feature is clearly observed for oxygen-deficient samples of the Cu-1212 [26,27] and (Pb 2/3 Cu 1/3 )-3212 [28] superconductors and also for the binary copper oxide Cu 2 O [29], all containing monovalent Cu in a linear coordination.) We analyzed the Cu L 3 -edge spectral features by fitting the intensities of the 931.2 and 932.7-eV peaks into a combination of Lorentzian and Gaussian functions after approximating the background to a straight line.…”

“…We analyzed the Cu L 3 -edge spectral features by fitting the intensities of the 931.2 and 932.7-eV peaks into a combination of Lorentzian and Gaussian functions after approximating the background to a straight line. The normalized integrated cross-section of the higher-energy peak, i.e., I 932.7 /(I 931.2 +I 932.7 ), should reflect (at least qualitatively) the extend of hole doping in the CuO 2 planes and the CuO 17d charge reservoir in average [24][25][26][27]. For the sake of an easier imagination, we convert this normalized intensity into an expression, V(Cu) XAS 2+I 932.7 /(I 931.2 +I 932.7 ), to get a number, that should be comparable to the chemical quantity of ''average nominal valence state of copper'' [30,31].…”