Holder, M.G.; Jesche, A.; Lombardo, P.; Hayn, R.; Vyalikh, D.V.; Kummer, K.; Danzenbächer, S.; Krellner, C.; Geibel, C.; Rienks, E.D.L.; Molodtsov, S.L.; Laubschat, C.: How chemical pressure affects the fundamental properties of rare-earth pnictides: An ARPES view. Physical Review B 86 (2012), p. 020506/1-5
10.1103/PhysRevB.86.020506

Abstract:
Angle-resolved photoelectron spectroscopy, supplemented by theoretical calculations has been applied to study the electronic structure of heavy-fermion material CeFePO, a homologue to the Fe-based high-temperature superconductors, and CeFeAs0.7P0.3O, where the applied chemical pressure results in a ferromagnetic order of the 4f moments. A comparative analysis reveals characteristic differences in the Fe-derived band structure for these materials, implying a rather different hybridization of valence electrons to the localized 4f orbitals. In particular, our results suggest that the ferromagnetism of Ce moments in CeFeAs0.7P0.3O is mediated mainly by Fe 3dxz/yz orbitals, while the Kondo screening in CeFePO is instead due to a strong interaction of Fe 3d3z2−r2 orbitals.