Fermi surface topology and quantum phase transitions in some Kondo systems

Orateur : Sébastien BURDIN (Laboratoire Ondes et Matière d'Aquitaine)

Fermi surfaces occupy a central place in solid state science since most of the physical properties of bulk metallic materials are governed by conduction electrons. Despite their apparent generality, Fermi surfaces are not always defined even in cristalline electronic systems. This is the case in strongly correlated materials, when electronic interactions drive the system to quantum phase transitions associated to Fermi surface instabilities. In this talk, we will focus on f-electron materials that are known to be characterized by rich phase diagramms including heavy-fermion, superconducting, magnetically ordered, hidden ordered and non-Fermi-liquid phases. From the theory side, we will address the issue of Fermi surface topology for two examples of Kondo systems : first, studying a Kondo alloy model on very greneral grounds, we will see how doping induces a Fermi surface instability which is a kind of Lifshitz transition. Then, considering a generalized Kondo lattice model, we will see how a carefull analysis of the Fermi surface topology can provide characteristical signatures of various kinds of order parameter, including Néel and spin-liquid orderings. Références : S. Burdin and C. Lacroix, PRL 110, 226403 (2013) X. Montiel, S. Burdin, C. Pépin, A. Ferraz, arXiv:1312.3653

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