Spectral Properties of the Generalized Spin-Fermion Models

TL;DR

This paper develops a non-perturbative Green's function approach to analyze the spectral properties of generalized spin-fermion models, capturing the interplay of localized and itinerant magnetic behaviors in correlated systems.

Contribution

It introduces a unified, self-consistent framework for calculating quasiparticle spectra and damping in generalized spin-fermion models using the Irreducible Green's Functions method.

Findings

Derived a comprehensive scheme for quasiparticle spectra with damping

Unified treatment of elastic and inelastic scattering effects

Demonstrated the model's flexibility in describing complex magnetic systems

Abstract

In order to account for competition and interplay of localized and itinerant magnetic behaviour in correlated many body systems with complex spectra the various types of spin-fermion models have been considered in the context of the Irreducible Green's Functions (IGF) approach. Examples are generalized d-f model and Kondo-Heisenberg model. The calculations of the quasiparticle excitation spectra with damping for these models has been performed in the framework of the equation- of-motion method for two-time temperature Green's Functions within a non-perturbative approach. A unified scheme for the construction of Generalized Mean Fields (elastic scattering corrections) and self-energy (inelastic scattering) in terms of the Dyson equation has been generalized in order to include the presence of the two interacting subsystems of localized spins and itinerant electrons. A general procedure is given to obtain the quasiparticle damping in a self-consistent way. This approach gives the complete and compact description of quasiparticles and show the flexibility and richness of the generalized spin-fermion model concept.