Dynamical Mean-Field Solution for a Model of Metal-Insulator Transitions in Moderately Doped Manganites

TL;DR

This paper introduces a new model for metal-insulator transitions in doped manganites, based on a disordered two-energy-level system and a disordered Kondo lattice, differing from traditional theories and aligning with experimental observations.

Contribution

It proposes a novel dynamical mean-field approach to a disordered Kondo lattice model for manganites, capturing unique transition mechanisms.

Findings

Model explains metal-insulator transition distinct from Anderson and Mott-Hubbard types.

Dynamical mean-field solution aligns well with experimental data.

Highlights role of spatially random two-energy-level systems in manganites.

Abstract

We propose that a specific spatial configuration of lattice sites that energetically favor {\it 3+} or {\it 4+} Mn ions in moderately doped manganites constitutes approximately a spatially random two-energy-level system. Such an effect results in a mechanism of metal-insulator transitions that appears to be different from both the Anderson transition and the Mott-Hubbard transition. Correspondingly, a disordered Kondo lattice model is put forward, whose dynamical mean-field solution agrees reasonably with experiments.