Heavy Fermion-like metal alpha double prime-Fe16N2 with giant saturation magnetization

TL;DR

This paper introduces a new model for the strong ferromagnetism in Fe16N2, inspired by heavy fermion systems, explaining its giant saturation magnetization through electron localization and correlation effects.

Contribution

It proposes a novel heavy fermion-like model for Fe16N2's ferromagnetism, highlighting the role of electron localization and correlation effects in achieving high magnetic moments.

Findings

Giant magnetic moments are achievable with high Hubbard U values.

Localized and itinerant electron coexistence is key to high saturation magnetization.

A new correlation effect within Fe-N clusters influences magnetic properties.

Abstract

A new model is proposed for the strong ferromagnetism associated with partially localized orbitals in the Fe16N2 metallic system which draws substantially from models of heavy fermion metals. We demonstrated that an unusual correlation effect is brought up within the Fe-N octahedral cluster region and the effective on-site 3d-3d Coulomb interaction increases due to a substantial 3d electrons charge density difference between the clusters and its surroundings, which leads to a partially localized high spin electron configuration with a long range ferromagnetic order. First principle calculation based on LDA+U method shows that giant magnetic moment can be achieved at sufficiently large Hubbard U value. The feature of the coexistence of the localized and itinerant electron states plays a key role on the formation of the giant saturation magnetization.