Multiple pre-edge structures in Cu K-edge x-ray absorption spectra of high-Tc cuprates revealed by high-resolution x-ray absorption spectroscopy - Laboratoire de Chimie Physique-Matière et Rayonnement Accéder directement au contenu
Article Dans Une Revue Physical Review Année : 2010

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

Résumé

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−xCuO2Cl2 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.

Dates et versions

hal-00644382 , version 1 (24-11-2011)

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Citer

C. Gougoussis, J.-P. Rueff, M. Calandra, M. d'Astuto, I. Jarrige, et al.. Multiple pre-edge structures in Cu K-edge x-ray absorption spectra of high-Tc cuprates revealed by high-resolution x-ray absorption spectroscopy. Physical Review, 2010, 81, pp.224519. ⟨10.1103/PhysRevB.81.224519⟩. ⟨hal-00644382⟩
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