Effective spinless fermions in the strong coupling Kondo model

TL;DR

This paper derives an effective spinless fermion model from the two-orbital Kondo-lattice model with classical spins, demonstrating its accuracy through simulations and analytical methods across various parameters.

Contribution

It introduces a novel effective model for strong Hund coupling in the Kondo lattice, validated by comparison with the original model.

Findings

Excellent agreement between the effective and original models across parameters

Identification of phase separation and phase diagram features

Observation of spectral properties including pseudo-gap formation

Abstract

Starting from the two-orbital Kondo-lattice model with classical t_2g spins, an effective spinless fermion model is derived for strong Hund coupling J_H with a projection technique. The model is studied by Monte Carlo simulations and analytically using a uniform hopping approximation. The results for the spinless fermion model are in remarkable agreement with those of the original Kondo-lattice model, independent of the carrier concentration, and even for moderate Hund coupling J_H. Phase separation, the phase diagram in uniform hopping approximation, as well as spectral properties including the formation of a pseudo-gap are discussed for both the Kondo-lattice and the effective spinless fermion model in one and three dimensions.