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Excitations électroniques dans les matériaux fortement corrélés: l'apport de la diffusion inélastique résonante des rayons X

Abstract : In this thesis, we studied electronic excitations in strongly correlated materials, in particular the transition metal monoxides CoO, NiO and CuO, the cuprate La2CuO4 and the nickelate La2NiO4. Resonant Inelastic X-ray Scattering (RIXS) was used to study the dynamics of low energy (few eV) excitations in these charge transfer insulators. This was possible thanks to instrumental development allowing an overall energy resolution improvement of a factor 3 to reach 300 meV.


In monoxides, we focused on localised crystal field excitations while in La2CuO4 and La2NiO4, our emphasis was on the measurement of charge transfer excitations. We observe a characteristic excitation identified as an excitonic feature (electron-hole bound state) in both materials with however a different dynamic behaviour. In La2CuO4, the exciton disperses while in La2NiO4 it is localised through antiferromagnetic correlations. A model invoking Zhang-Rice singlet formation in the cuprate has been proposed to explain the dynamics of the exciton in the antiferromagnetic background.
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https://tel.archives-ouvertes.fr/tel-00113361
Contributor : Emilie Collart <>
Submitted on : Monday, November 13, 2006 - 11:02:19 AM
Last modification on : Wednesday, December 9, 2020 - 3:12:28 PM
Long-term archiving on: : Tuesday, April 6, 2010 - 10:21:39 PM

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  • HAL Id : tel-00113361, version 1

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Emilie Collart. Excitations électroniques dans les matériaux fortement corrélés: l'apport de la diffusion inélastique résonante des rayons X. Matière Condensée [cond-mat]. Université Pierre et Marie Curie - Paris VI, 2005. Français. ⟨tel-00113361⟩

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