Finite f-Electron Bandwidth in a Heavy Fermion Model
Abstract
Determinant Quantum Monte Carlo (DQMC) is used to study the effect of non-zero hopping tf in the localized f-band of the periodic Anderson model (PAM) in two dimensions. The low temperature properties are determined in the plane of interband hybridization V and tf at fixed Uf and half-filling, including the case when the sign of tf is opposite to that of the conduction band td. For tf and td of the same sign, and when tf=td > (V =4td)2, the non-interacting system is metallic. We show that a remnant of the band insulator to metal line at Uf = 0 persists in the interacting system, manifesting itself as a maximal tendency toward antiferromagnetic correlations at low temperature. In this optimal tf region, short range (e.g. near-neighbor) and long-range spin correlations develop at similar temperatures and have comparable magnitude. Both observations are in stark contrast with the situation in the widely studied PAM (tf = 0) and single band Hubbard model, where short range correlations are stronger and develop at higher temperature. The effect that finite tf has on Kondo screening is investigated by considering the evolution of the local density of states for selected tf as a function of V . We use mean field theory as a tool to discriminate those aspects of the physics that are genuinely many-body in character.
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