How chemical pressure affects the fundamental properties of rare-earth   pnictides: an ARPES view
  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 CeFeAs_0.7P_0.3O, 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 CeFeAs_0.7P_0.3O is mediated mainly by Fe 3d_xz/yz orbitals, while the Kondo screening in CeFePO is instead due to a strong interaction of Fe 3d_3z^2-r^2 orbitals. 
M. G. Holder, A. Jesche, P. Lombardo, R. Hayn, D. V. Vyalikh, K.   Kummer, S. Danzenb\"acher, C. Krellner, C. Geibel, E. D. ...
cond-mat.supr-con cond-mat.str-el