Absolute evaluation of combined hybridization-induced and RKKY-induced two-ion interaction in correlated electron systems

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Abstract
Cerium and light actinidematerials have unusual properties, including suppressed crystal‐field splitting and highly anisotropic ordered magnetism, that can be understood on the basis of the Coulomb interaction between partially delocalized f electrons and the non‐f‐band electrons. In setting the absolute scale of interaction energy for materially predictive theory, it is crucial to take account of all consequences of the Coulomb interaction which contribute to the two‐ion interaction. These include both the hybridization‐induced effect (i.e., band‐f mixing effects treated by a one‐electron potential) and the RKKY‐type effect (arising from the band‐fexchange interaction) and the cross effect. The RKKY interaction, when treated fully, provides both isotropic and anisotropic contributions to the two‐ion interaction. We found the anisotropic part is similar in its angular dependence and range dependence to the hybridization‐induced effects. Therefore, the qualitative anisotropic nature of observable magnetic effects is quite similar to that caused by hybridization‐induced effects by themselves, but the scale of energy is changed. Our results for CeBi and CeSb are in agreement with both the qualitative nature of the magnetic ordering and crystal‐field dressing and with the absolute scale of energy as shown by the Néel temperature.