Basis of strong change of hybridization-induced magnetic ordering between CeSb and CeTe

A sharp change in the nature of the magnetic ordering has been observed on going from CeSb to CeTe, both of which have NaC1 structures with a small decrease in lattice parameter. This is an interesting example of the way in which hybridization of partially delocalized f electrons with band electrons gives rise to highly unusual magnetic properties which show great chemical sensitivity. In the present paper we apply our previous ab initio treatment of hybridization-induced effects to investigate this striking change in magnetic behavior. We have performed self-consistent warped muffin-tin LMTO band calculations treating the Ce 4f states as resonance states that are constrained to be localized. Compared to CeSb, the anion-derived p bands in CeTe sink well below the Fermi energy, thus strongly changing the band-f hybridization. We have calculated the hybridization dressing of the crystal-field levels and the anisotropic two-ion exchange interaction and compared them with those calculated for CeSb and with experiment. A strong decrease in the two-ion interaction explains the drastic change in observed magnetic behavior between CeSb and CeTe