A magnetic tight-binding model: correlations in ferromagnetic transition metals

TL;DR

This paper develops a tight-binding model incorporating correlation effects for ferromagnetic transition metals, adjusting Coulomb parameters to match first-principles results and accurately describing their magnetic properties.

Contribution

It introduces a formalism that accounts for sp-band effects in the tight-binding model, providing corrected onsite Coulomb parameters for Fe, Co, and Ni.

Findings

Corrected Coulomb parameters: 1.3 eV for Fe, 1.5 eV for Co, 2.1 eV for Ni.

Accurate description of ferromagnetism within the tight-binding framework.

Analysis of sp-d hybridization effects on electronic correlations.

Abstract

Correlations derived through single-particle approximations of the many-body problem frequently result in erroneously inflated or diminished physical properties. In the context of transition metals, the impact of correlations can be assessed by analyzing the effect of the delocalized sp-band on the d-band. The tight-binding approach is studied in the d-band approximation, considering and excluding the influence of sp-d hybridization. The impact of the delocalized sp-band induces a correction to the onsite Coulomb parameter. This formalism enables an accurate description of the ferromagnetism within the tight-binding approximation. The onsite Coulomb corrections, which were calculated in accordance with first-principles results, are 1.3 eV for bcc iron, 1.5 eV for fcc cobalt, and 2.1 eV for fcc nickel.