Institut des Sciences Moléculaires d'Orsay



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Accueil > Séminaires > Année 2021 > Séminaire de David Pinek (26 mai)

Séminaire de David Pinek (26 mai)

Grenoble institute of Technology, LMGP

par Martrenchard-Barra Séverine - 12 mai 2021 (modifié le 30 août 2021)

Le séminaire sera diffusé en visioconférence.

Exploring the electronic structure of Mn+1AXn nanolamellar carbides and their derivatives

The Mn+1AXn, or “MAX” phases, where M is an early transition metal, A belongs to group 13-16 of the periodic table and X is C or N, are a class of nano-layered compounds that have sparked a strong interest from the material science community for their unique combinations of metal-like and ceramic-like properties. They are also precursors for MXENES, a whole family of two dimensional carbides obtained by exfoliation of 3D MAX phases and notably sought for energy storage developments. Up to 155 MAX phases have been discovered up to now. Despite MAX phases’ attractiveness for a wide range of applications, the origins of several of their fundamental features are still under debate, notably regarding the relationships between their electronic structure, anisotropies and transport properties.

We present here the methodology we followed to grow MAX phase single crystals and experimentally determine the morphology of the electronic states (e.g. Band structure and Fermi surface) of Cr2AlC, V2AlC and Ti3SiC2. The output of angle resolved photoemission spectroscopy experiments carried out on single crystals are compared with density functional theory calculations. The respective anisotropies of the Fermi surfaces are discussed with respect to the transport coefficients of each phase. The derivation of rigid band models that can describe the electronic structure of M2AC -or “211” MAX phases- is then developed. From there, we will discuss the prospects of the potential exploration of (MxN1-x)2AX solid solutions for tuning the position of the Fermi level in order to reach topological nodes within the band structure of 211 MAX phases. Finally, MAX phases magnetic derivatives -iMAX and 4473 phases- will be briefly introduced and evidences of the interplay between Kondo and ferromagnetic interactions in Mo4Ce4Al7C3 will be presented.