Interplay of localized and itinerant behavior in the one-dimensional   Kondo-Heisenberg model
  We use the density matrix renormalization group method to study the interplay of the localized and itinerant behaviors in the one-dimensional Kondo-Heisenberg model. We find signatures of simultaneously localized and itinerant behaviors of the local spins and attribute this duality to their simultaneous entanglement within the spin chain and with conduction electrons due to incomplete hybridization. We propose a microscopic definition of the hybridization parameter that measures this "partial" itinerancy. Our results provide a microscopic support for the dual nature of f-electrons and the resulting two-fluid behavior widely observed in heavy electron materials. 
Neng Xie and Yi-feng Yang
cond-mat.str-el