Mo4Ce4Al7C3 : A nanolamellar ferromagnetic Kondo lattice
Résumé
Herein we show that Mo4Ce4Al7C3, a recently discovered nanolamellar compound displaying mixed valence,
combines Kondo lattice behavior with ferromagnetism. A sizeable magnetization is carried by 3p states of Al as evidenced by a strong x-ray magnetic circular dichroism signal at the K edge of aluminum, whereas no
detectable signal was observed at the K edge of carbon and L2,3 edges of molybdenum. These results point out
that the ferromagnetic behavior originates in the Ce atoms with 4 f 1 electronic configuration lying within the Al
planes. The evolution with pressure of the mixed valence of Ce atoms in the Mo-C planes determined via Ce
L3 x-ray-absorption spectra along with the magnetoresistance measurements across the ferromagnetic transition unambiguously reveal a Kondo behavior. Angle-resolved photoemission spectroscopy and density functional theory confirm a certain degree of Ce 4 f electron delocalization. More generally, conduction electrons are not restricted to lie in the MoC planes but are also delocalized in the Al planes.
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