The characterization of Co-nanoparticles supported on graphene

TL;DR

This study combines DFT calculations and spectroscopic measurements to analyze Co-nanoparticles on graphene, revealing oxidation behavior and ferromagnetic properties relevant for spintronics applications.

Contribution

It provides new insights into the oxidation states and magnetic properties of Co-nanoparticles supported on graphene, combining theoretical and experimental approaches.

Findings

Co atoms form islands at low coverage and become oxidized in air.

At 2 nm coverage, the top Co layers oxidize while the lower layers remain metallic.

Oxide layer formation enables ferromagnetic properties suitable for spin filters.

Abstract

The results of density functional theory (DFT) calculations and measurements of X-ray photoelectron (XPS) and X-ray emission (XES) spectra of Co-nanoparticles dispersed on graphene/Cu composites are presented. It is found that for 0.02nm and 0.06nm Co coverage the Co atoms form islands which are strongly oxidized under exposure at the air. For Co (2nm) coverage the upper Co-layers is oxidized whereas the lower layers contacting with graphene is in metallic state. Therefore Co (2 nm) coverage induces the formation of protective oxide layer providing the ferromagnetic properties of Co nanoparticles which can be used as spin filters in spintronics devices.