Using high-resolution x-ray absorption spectroscopy and state-of-the-art electronic structure calculations we demonstrate that the pre-edge region at the Cu K edge of high- Tc cuprates is composed of several excitations invisible in standard x-ray absorption spectra. We consider in detail the case of Ca2-x CuO2 Cl2 and show that the many pre-edge excitations (two for c -axis polarization, four for in-plane polarization and out-of-plane incident x-ray momentum) are dominated by off-site transitions and intersite hybridization. This demonstrates the relevance of approaches beyond the single-site model for the description of the pre edges of correlated materials. Finally, we show the occurrence of a doubling of the main edge peak that is most visible when the polarization is along the c axis. This doubling, that has not been seen in any previous absorption data in cuprates, is not reproduced by first-principles calculations. We suggest that this peak is due to many-body charge-transfer excitations while all the other visible far-edge structures are single particle in origin. Our work indicates that previous interpretations of the Cu K -edge x-ray absorption spectra in high- Tc cuprates can be profitably reconsidered. © 2010 The American Physical Society.

Multiple pre-edge structures in Cu K -edge x-ray absorption spectra of high- Tc cuprates revealed by high-resolution x-ray absorption spectroscopy / Gougoussis, C.; Rueff, J. -P.; Calandra, M.; D'Astuto, M.; Jarrige, I.; Ishii, H.; Shukla, A.; Yamada, I.; Azuma, M.; Takano, M.. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - 81:22(2010). [10.1103/PhysRevB.81.224519]

Multiple pre-edge structures in Cu K -edge x-ray absorption spectra of high- Tc cuprates revealed by high-resolution x-ray absorption spectroscopy

Calandra M.;
2010-01-01

Abstract

Using high-resolution x-ray absorption spectroscopy and state-of-the-art electronic structure calculations we demonstrate that the pre-edge region at the Cu K edge of high- Tc cuprates is composed of several excitations invisible in standard x-ray absorption spectra. We consider in detail the case of Ca2-x CuO2 Cl2 and show that the many pre-edge excitations (two for c -axis polarization, four for in-plane polarization and out-of-plane incident x-ray momentum) are dominated by off-site transitions and intersite hybridization. This demonstrates the relevance of approaches beyond the single-site model for the description of the pre edges of correlated materials. Finally, we show the occurrence of a doubling of the main edge peak that is most visible when the polarization is along the c axis. This doubling, that has not been seen in any previous absorption data in cuprates, is not reproduced by first-principles calculations. We suggest that this peak is due to many-body charge-transfer excitations while all the other visible far-edge structures are single particle in origin. Our work indicates that previous interpretations of the Cu K -edge x-ray absorption spectra in high- Tc cuprates can be profitably reconsidered. © 2010 The American Physical Society.
2010
22
Gougoussis, C.; Rueff, J. -P.; Calandra, M.; D'Astuto, M.; Jarrige, I.; Ishii, H.; Shukla, A.; Yamada, I.; Azuma, M.; Takano, M.
Multiple pre-edge structures in Cu K -edge x-ray absorption spectra of high- Tc cuprates revealed by high-resolution x-ray absorption spectroscopy / Gougoussis, C.; Rueff, J. -P.; Calandra, M.; D'Astuto, M.; Jarrige, I.; Ishii, H.; Shukla, A.; Yamada, I.; Azuma, M.; Takano, M.. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - 81:22(2010). [10.1103/PhysRevB.81.224519]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11572/261774
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