Single 3$d$ transition metal atoms on multi-layer graphene systems: electronic configurations, bonding mechanisms and role of the substrate

TL;DR

This study investigates the electronic configurations and bonding mechanisms of 3d transition metal adatoms on graphene and graphite, revealing how substrate interactions influence magnetic properties and bonding nature.

Contribution

It provides detailed insights into the interplay of long-range and local interactions affecting adatom bonding and magnetism on layered carbon substrates.

Findings

Fe and Co are physisorbed with different 3d-shell occupancies on graphene and graphite.

Ni and Cu tend towards chemisorption, quenching magnetic moments.

Substrate type significantly influences adatom electronic and magnetic properties.

Abstract

The electronic configurations of Fe, Co, Ni, and Cu adatoms on graphene and graphite have been studied by x-ray magnetic circular dichroism and charge transfer multiplet theory. A delicate interplay between long-range interactions and local chemical bonding is found to influence the adatom equilibrium distance and magnetic moment. The results for Fe and Co are consistent with purely physisorbed species having, however, different 3$d$-shell occupancies on graphene and graphite ($d^{n+1}$ and $d^n$, respectively). On the other hand, for the late 3$d$ metals Ni and Cu a trend towards chemisorption is found, which strongly quenches the magnetic moment on both substrates.