Electronic structure and magnetic properties of graphene/Co composite

The results of measurements of XPS spectra and magnetic properties of powder graphene/Co composite prepared by hydrogen reduction of CoCl2·6H2O deposited on few-layers graphene matrix are presented. XPS Co 2p measurements show two sets of 2p3/2,1/2-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.