Soft-x-ray absorption spectroscopy of Nd{sub 1+x}Ba{sub 2{minus}x}Cu{sub 3}O{sub 7+{delta}} (x=0{endash}0.6)
- Synchrotron Radiation Research Center (SRRC), Hsinchu, Taiwan, Republic of (China)
- Department of Chemistry, National Taiwan University, Taipei, Taiwan, Republic of (China)
- Ames Laboratory, Iowa State University, Ames, Iowa 50011 (United States)
O K-edge and Cu L{sub 23}-edge x-ray-absorption near-edge-structure spectra for the series of Nd{sub 1+x}Ba{sub 2{minus}x}Cu{sub 3}O{sub 7+{delta}} compounds (x=0{endash}0.6) were measured using a bulk-sensitive x-ray fluorescence yield technique. Near the O 1s edge, pre-edge peaks at {approximately}527.5 and {approximately}528.2 eV are ascribed to the excitations of O 1s electrons to O 2p holes located in the CuO{sub 3} ribbons and CuO{sub 2} planes, respectively. The peak at {approximately}528.2 eV decreases in intensity with increasing the Nd doping, indicating the filling of holes in the CuO{sub 2} planes by the substitution of Nd{sup 3+} for Ba{sup 2+} in the Nd{sub 1+x}Ba{sub 2{minus}x}Cu{sub 3}O{sub 7+{delta}} system. For low levels of Nd doping, the holes are located mainly in the CuO{sub 2} planes. At higher Nd doping, the holes are located predominantly in the CuO{sub 3} ribbons. The depression in T{sub c} for the Nd{sub 1+x}Ba{sub 2{minus}x}Cu{sub 3}O{sub 7+{delta}} system correlates closely with the hole concentration in the CuO{sub 2} planes and the number of disrupted fourfold-coordinated Cu on the chain sites. The high-energy shoulders in the Cu L{sub 23}-edge absorption spectra arise from Cu3d{sup 9}L defected states to Cu2p{sup {minus}1}3d{sup 10}L excited states, where L denotes the ligand hole on the CuO{sub 3} ribbons and CuO{sub 2} planes. With increasing the Nd doping, the shoulders shift to higher energy {approximately}0.3 eV from x=0 to 0.6. {copyright} {ital 1997} {ital The American Physical Society}
- OSTI ID:
- 450375
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 55, Issue 5; Other Information: PBD: Feb 1997
- Country of Publication:
- United States
- Language:
- English
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