Quasiparticle Dynamics in the Kondo Lattice Model at Half Filling

TL;DR

This paper investigates quasiparticle behavior in the Kondo lattice model at half filling, revealing how antiferromagnetic correlations influence quasiparticle dispersions and lead to the formation of antibound states linked to spin fluctuations.

Contribution

It provides a detailed analysis of quasiparticle spectral properties and the emergence of antibound states in the Kondo lattice model in one and two dimensions, highlighting the role of antiferromagnetic correlations.

Findings

Antiferromagnetic correlations modify quasiparticle dispersions.

Repulsive interactions lead to antibound states above the two-quasiparticle continuum.

Antibound states exhibit extended s-wave symmetry on the square lattice.

Abstract

We study spectral properties of quasiparticles in the Kondo lattice model in one and two dimensions including the coherent quasiparticle dispersions, their spectral weights and the full two-quasiparticle spectrum using a cluster expansion scheme. We investigate the evolution of the quasiparticle band as antiferromagnetic correlations are enhanced towards the RKKY limit of the model. In both the 1D and the 2D model we find that a repulsive interaction between quasiparticles results in a distinct antibound state above the two-quasiparticle continuum. The repulsive interaction is correlated with the emerging antiferromagnetic correlations and can therefore be associated with spin fluctuations. On the square lattice, the antibound state has an extended s-wave symmetry.