Joint intercalation of ultrathin Fe and Co films under a graphene buffer layer on a SiC(0001) single crystal

The joint intercalation of Co and Fe atoms under a graphene buffer layer synthesized on a SiC(0001) single crystal has been studied. Intercalation has been performed by means of the alternating deposition of ultrathin Fe and Co metal films on the substrate heated to 450$^\circ$ C with the subsequent heating to 600$^\circ$ C in 15 min. It has been shown that Co and Fe atoms under these conditions are intercalated under graphene, forming compounds with silicon and with each other. The existence of a magnetic order in the system up to room temperature has been demonstrated using a superconducting quantum interferometer. A possible stoichiometry of the formed alloys has been analyzed using data on the shape and magnitude of hysteresis loops. In addition, it has been found that Fe and Co in the system exposed to the atmosphere are not oxidized. Thus, graphene protects the formed system. This study makes contribution to the investigation of graphene in contact with magnetic metals and promotes its application in spintronic and nanoelectronic devices.