Metal-insulator transition in a doubly orbitally degenerate model with correlated hopping

TL;DR

This paper introduces a doubly orbitally degenerate model with correlated hopping, accounting for intersite electron interactions, and analyzes the conditions for metal-insulator transitions at various electron concentrations.

Contribution

It presents a novel model incorporating intersite electron-electron interactions and correlated hopping, with analytical calculations of the energy spectrum and transition criteria.

Findings

Energy gap width depends on electron concentration.

Metal-insulator transition criteria are derived for different Hund's coupling regimes.

The model predicts concentration-dependent effective hopping.

Abstract

In the present paper we propose a doubly orbitally degenerate narrow-band model with correlated hopping. The peculiarity of the model is taking into account the matrix element of electron-electron interaction which describes intersite hoppings of electrons. In particular, this leads to the concentration dependence of the effective hopping integral. The cases of the strong and weak Hund's coupling are considered. By means of a generalized mean-field approximation the single-particle Green function and quasiparticle energy spectrum are calculated. Metal-insulator transition is studied in the model at different integer values of the electron concentration. With the help of the obtained energy spectrum we find energy gap width and criteria of metal-insulator transition.