Interplay of crystal field structures with $f^2$ configuration to heavy fermions

TL;DR

This paper investigates how crystal field structures influence quasiparticle states in the $f^2$ Anderson lattice model, revealing complex band formations and residual interactions that affect magnetic properties.

Contribution

It demonstrates the formation of multiple quasiparticle bands and the impact of crystal field ground states on residual interactions and magnetic susceptibility in heavy fermion systems.

Findings

Multiple quasiparticle bands form near the Fermi level depending on crystal field states.

Residual interactions among quasiparticles are influenced by the crystal field ground state.

Antiferromagnetic interactions suppress spin susceptibility despite heavy quasiparticle mass.

Abstract

We examine a relevance between characteristic of crystal field structures and heavily renormalized quasiparticle states in the $f^0$-$f^1$-$f^2$ Anderson lattice model. Using a slave-boson mean-field approximation, we find that for $f^2$ configurations two or three quasiparticle bands are formed near the Fermi level depending on the number of the relevant $f^1$ orbitals in the $f^2$ crystal field ground state. The inter-orbital correlations characterizing the crystal field ground state closely reflect in inter-band residual interactions among quasiparticles. Particularly in the case of a singlet crystal field ground state, resulting residual antiferromagnetic exchange interactions among the quasiparticles lead to an anomalous suppression of the quasiparticle contribution of the spin susceptibility, even though the quasiparticle mass is strongly enhanced.