AIP Digital Archive
The magnetic ordering behavior of correlated f-electron systems varies widely. With regard to the value of the ordered moments, there are systems of saturated moment (e.g., CeSb), of moment somewhat reduced from the saturated value (e.g., UTe), of very small moment (e.g., UPt3) and of no moment at all (e.g., CeCu2Si2). We show that such wide diversity in magnetic ordering is a manifestation of the competition between (1) hybridization and exchange interaction and (2) localization and itinerancy. By analyzing these effects, we develop a theory which organizes the diverse magnetic behavior into a unified picture describable through one model Hamiltonian. An important feature of this analysis is that we recognize and treat the effect of band-f Coulomb exchange simultaneously with that of band-f hybridization. Rather than adopting the standard analysis using the "Kondo resonance''–"Kondo compensation'' concept, the development of this theory offers a new approach to treat the correlated f-electron state. The present theory naturally leads to a nonmagnetic singlet "Kondo state'' which is one of the possible states, along with other magnetic states which the system could be in, when the conditions determining the state of the system favor that choice. The f orbital motions and spin-orbital coupling are given full consideration in the theory.
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