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Theses

Etude structurale de BaVS3: un conducteur quasi-1D à électrons fortement corrélés

Abstract : BaVS3 is a one-dimensional compound made by chains of face sharing octahedron of VS6. This compound is metallic at room temperature and shows strong electronic correlations. Two kinds of electrons are involved in this compound: dz2 electrons delocalized along the chain axis and localized e(t2g) electrons.

Several phase transitions happen in temperature: at 240 K a structural transition, at 70 K a metal-insulator transition and at 30 K a magnetic transition. The point of this thesis is the study of the metal-insulator transition from a structural point of view with X-ray scattering.

A structural transition associated with the metal-insulator one was evidenced by the appearance of a superstructure announced by a one dimensional pretransitional fluctuation regime. The low temperature structure has been refined with a high resolution powder scattering. With anomalous scattering, the absence of a charge order was shown.

This transition is interpreted as a Peierls like transition. A model which implies charge density waves on both types of electron is
proposed to explain the absence of charge order. This model implies an orbital ordering.

Substituted samples were also observed. These samples show a sulfur deficiency which seems to be responsible of strong changes of properties in comparison with the pure compound.
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https://tel.archives-ouvertes.fr/tel-00011693
Contributor : Sébastien Fagot <>
Submitted on : Monday, February 27, 2006 - 5:08:26 PM
Last modification on : Wednesday, September 16, 2020 - 4:32:23 PM
Long-term archiving on: : Tuesday, April 6, 2010 - 4:45:24 PM

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  • HAL Id : tel-00011693, version 1

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Sébastien Fagot. Etude structurale de BaVS3: un conducteur quasi-1D à électrons fortement corrélés. Matière Condensée [cond-mat]. Université Paris-Diderot - Paris VII, 2005. Français. ⟨tel-00011693⟩

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