Anomalous Pr ordering, Pr L-3-edge and CuK-edge XANES studies for the insulating PrBa2Cu3O7-y system

作者：Lin BN^*; Lin YX; Hsu YY; Liao JD; Cheng WH; Lee JF; Jang LY; Ku HC

来源：Journal of Low Temperature Physics, 2003, 131(5-6): 803-807.

DOI：10.1023/A:1023470808853

X-ray absorption near-edge structure (XANES) data for the PrBa2Cu3O7-y (6.21 less than or equal to 7-y less than or equal to 6.95) insulating system with anomalous Pr antiferromagnetic order are reported. Pr L-3-edge XANES indicates that Pr formal valence decreases from 3.17-3.18 for oxygenated samples to 3.09 for oxygen-depleted PrBa2 Cu-3 O-6.43, 3.03 for PrBa2 Cu-3 O-6.38 and 3.01 for PrBa2 Cu-3 O-6.21. The variation of Pr valence indicates that the doped holes initially stay in the CuO1-y plane and contribute to Cu(I)-Cu(II) transformation in this plane, but gradually move into the CuO2 bi-layers with PrO8 cage and result in the appearance of Pr(IV) localized-hole state with increasing oxygen content. Cu K-edge XANES indicates that the average Cu formal valence increases from less than 2 in oxygen-depleted region to a value larger than 2 for oxygenated samples, with the estimated Cu valence of 2.24 for PrBa2 Cu-3 O-6.95. The small average Cu formal valence or large Pr formal valence is closely related to the absence of superconductivity.

• 出版日期2003-6
• 单位清华大学