Rare-earth (RE) nanolaminates Mo4RE4Al7C3 featuring ferromagnetism and mixed-valence states
Résumé
Rare-earth-based (RE) nanolaminates have attracted attention recently because of their complicated magnetism and their potential as precursors for strongly correlated two-dimensional materials. In this work, we synthesized a class of nanolaminates with a Mo4RE4Al7C3 chemistry, where RE = Ce or Pr. Powder samples of both phases were characterized with respect to structure and composition. Single crystals of Mo4Ce4Al7C3 were used for magnetization measurements. The crystal structure was investigated by means of x-ray diffraction and scanning transmission electron microscopy. Magnetization analysis reveals a ferromagnetic ground state with a Curie temperature of similar to 10.5 K. X-ray absorption near-edge structure provides experimental evidence that Ce is in a mixed-valence state. X-ray magnetic circular dichroism shows that only the Ce atoms with 4f(1) configuration occupying one of the two possible sites are ferromagnetically coupled, with a saturation moment of similar to 1.2 mu(B) per atom. We thus classify Mo4Ce4Al7C3 as a ferromagnetic, mixed-valence compound.