The One-Orbital Model: Phase Diagram and Dominant Correlations

Abstract

This chapter describes the main results available in the context of the one-orbital model for manganites. This model appears in the literature also as the ferromagnetic Kondo model or the double-exchange model. We use the name “one-orbital model” to highlight the differences with the more realistic two-orbital model with Jahn Teller phonons, also analyzed extensively in this book. The information provided in this chapter includes phase diagrams and dominant ordering tendencies in the ground state. It also includes the regimen of electronic phase separation believed to be of relevance for Mn oxides. A similar phenomenon, although not involving ferromagnetism, has been widely discussed in the Cu oxide literature as well [1.3]. This chapter also contains a brief review by A. Moreo of related spin-fermion models used in the context of high-T c superconductors. A simple model of interacting localized spins and mobile electrons clearly finds applications in several contexts, including also heavy fermions and diluted magnetic semiconductors.KeywordsMonte Carlo TechniqueClassical SpinSpin Spin CorrelationFlux PhaseElectronic Phase SeparationThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.