Trends in the magnetic properties of Fe, Co and Ni clusters and monolayers on Ir(111), Pt(111) and Au(111)

TL;DR

This study uses relativistic ab-initio calculations to analyze how atomic magnetic moments, exchange interactions, and magnetic anisotropy vary with element, size, and substrate in small Fe, Co, and Ni clusters on Ir(111), Pt(111), and Au(111).

Contribution

It provides detailed element-specific and size-dependent insights into magnetic properties of transition metal clusters on noble metal surfaces using advanced density functional theory methods.

Findings

Atomic spin moments decrease linearly with coordination.

Exchange interactions are stronger in Fe and Co clusters than in bulk.

Ni clusters tend to exhibit noncollinear magnetism.

Abstract

We present a detailed theoretical investigation on the magnetic properties of small single-layered Fe, Co and Ni clusters deposited on Ir(111), Pt(111) and Au(111). For this a fully relativistic {\em ab-initio} scheme based on density functional theory has been used. We analyse the element, size and geometry specific variations of the atomic magnetic moments and their mutual exchange interactions as well as the magnetic anisotropy energy in these systems. Our results show that the atomic spin magnetic moments in the Fe and Co clusters decrease almost linearly with coordination on all three substrates, while the corresponding orbital magnetic moments appear to be much more sensitive to the local atomic environment. The isotropic exchange interaction among the cluster atoms is always very strong for Fe and Co exceeding the values for bulk bcc Fe and hcp Co, whereas the anisotropic Dzyaloshinski-Moriya interaction is in general one or two orders of magnitude smaller when compared to the isotropic one. For the magnetic properties of Ni clusters the magnetic properties can show quite a different behaviour and we find in this case a strong tendency towards noncollinear magnetism.