Cross effect of Coulomb correlation and hybridization in the occurrence of ferromagnetism in two shifted band transition metals

TL;DR

This paper investigates how Coulomb correlation and hybridization influence ferromagnetism in a two-band transition metal model, revealing conditions for magnetic ordering through a self-consistent effective Hamiltonian approach.

Contribution

It introduces a model combining correlated and uncorrelated bands with hybridization and derives an effective Hamiltonian to study ferromagnetism.

Findings

Ferromagnetism arises for specific parameter ranges.

Self-energy and density of states show exchange splitting.

Electron-spin polarization depends on interaction and hybridization parameters.

Abstract

In this work we discuss the occurrence of ferromagnetism in transition-like metals. The metal is represented by two hybridized($V$) and shifted $(\epsilon_s$) bands one of which includes Hubbard correlation whereas the other is uncorrelated. The starting point is to transform the original Hamiltonian into an effective one. Only one site retains the full correlation (U) while in the others the correlations are represented by an effective field, the self-energy(single-site approximation). This field is self-consistently determined by imposing the translational invariance of the problem. Thereby one gets an exchange split quasi-particle density of states and then an electron-spin polarization for some values of the parameters $(U,V, \alpha, \epsilon_s)$, $\alpha$ being the ratio of the effective masses of the two bands and of the occupation number $n$.