Electronic structure and magnetic properties of graphene/Co composites

TL;DR

This study investigates the electronic and magnetic properties of graphene/Co composites, revealing partial oxidation of cobalt and the preservation of ferromagnetic properties, which are promising for spintronics applications.

Contribution

It provides experimental insights into the oxidation states and magnetic behavior of graphene/Co composites, highlighting their potential in spintronics.

Findings

Cobalt in the composite is partly oxidized.

Oxide layer preserves ferromagnetism in ambient conditions.

Magnetic hysteresis confirms ferromagnetic properties are maintained.

Abstract

The results of measurements of XPS spectra and magnetic properties of graphene/Co composites prepared by adding of CoCl$_2$x6H$_2$O diluted in ethyl alcohol to highly-splitted graphite are presented. XPS Co 2p measurements show two sets of 2p$_{3/2,1/2}$-lines belonging to oxidized and metallic Co-atoms. This means that metal in composite is partly oxidized. This conclusion is confirmed by magnetic measurements which show the presence of the main (from the metal) and shifted (from the oxide) hysteresis loops. The presence of oxide layer on the metal surface prevents the metal from the full oxidation and (as shown by magnetic measurements) provides the preservation of ferromagnetic properties after long exposure in ambient air which enables the use of graphene/metal composites in spintronics devices.