Effective spinless fermions in the strong coupling Kondo model

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Starting from the two-orbital Kondo-lattice model with classical t₂g spins, an effective spinless fermion model is derived for strong Hund coupling Jₕ 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 Jₕ. 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.