Layer-resolved magnetic exchange interactions of surfaces of late 3d elements: effects of electronic correlations

TL;DR

This study uses advanced ab initio methods to analyze the magnetic exchange interactions and electronic structure of Fe, Co, and Ni surfaces, revealing how electronic correlations influence magnetic properties and surface states.

Contribution

It provides a detailed ab initio analysis combining density functional theory and dynamical mean-field theory to understand surface magnetic interactions in late 3d elements, highlighting correlation effects.

Findings

Surface states enhance magnetic moments and exchange couplings.

Fe surfaces tend to have antiferromagnetic coupling between atoms.

Correlations increase orbital magnetic moments but do not drastically alter exchange interactions.

Abstract

We present the results of an ab initio study of magnetic properties of Fe, Co and Ni surfaces. In particular, we discuss their electronic structure and magnetic exchange interactions (Jij), as obtained by means of a combination of density functional theory and dynamical mean-field theory. All studied systems have a pronounced tendency to ferromagnetism both for bulk and surface atoms. The presence of narrow-band surface states is shown to enhance the magnetic moment as well as the exchange couplings. The most interesting results were obtained for the Fe surface where the atoms have a tendency to couple antiferromagnetically with each other. This interaction is relatively small, when compared to interlayer ferromagnetic interaction, and strongly depends on the lattice parameter. Local correlation effects are shown to lead to strong changes of the overall shape of the spectral functions. However, they seem to not play a decisive role on the overall picture of the magnetic couplings studied here. We have also investigated the influence of correlations on the spin and orbital moments of the bulk-like and surface atoms. We found that dynamical correlations in general lead to enhanced values of the orbital moment.