Ferromagnetism in two band metals: Combined effect of Coulomb correlation, hybridization and band widths

TL;DR

This paper investigates the emergence of ferromagnetism in two-band metals considering Coulomb correlation, hybridization, and band widths, using an effective Hamiltonian and self-consistent calculations.

Contribution

It introduces a simplified effective Hamiltonian approach to analyze ferromagnetism in two-band metals with correlated and uncorrelated bands, incorporating self-consistency.

Findings

Self-consistent internal field influences magnetic ordering.

Band width and shift ratios affect ferromagnetic stability.

Comparison of spin-dependent and paramagnetic free energies reveals ferromagnetic conditions.

Abstract

We study the possibility of ferromagnetism in metals. The metal is described by two hybridized bands one of which includes Hubbard correlation whereas the other is uncorrelated. We parametrize the ratio of the band widths and their centers as well. The original Hamiltonian is transformed in an effective and simpler one. Only one site retains the full correlation (U) while in the others acts as an internal field, the self-energy, in the framework of an alloy analogy approximation. This field, in turn, is self-consistently determined by imposing the translational invariance of the problem. For several total electronic occupation numbers (n_{total}) we compare the spin dependent free energies with the corresponding paramagnetic ones. We present several results pointing out the mechanism by which the self-consistency introduces a sort of constraints, for given values of band width and band shift .