Fabrication of new magnetic devices with desired properties [1,2] requires more and more the ability to control the strength of competing contributions to magnetic anisotropy (MA).In this respect, low dimensional, nano-sized magnetic hetero-structures represent an extremely appealing platform for future developments. For instance, interface, adsorbate or capping layer –induced interactions can dramatically change the MA, enabling control on the easy magnetization direction. Very recently, graphene (Gr) induced stabilization of out of plane magnetism in Co thin films was demonstrated . Here we discuss how formation of surface carbides also promotes a Spin Reorientation Transition (SRT) in few layer Co thin films. Carbon accumulation achieved throughfocused-beam dissociation of CO is exploited to lithographically graft chemical patterns, locally modifying the electronic and magnetic properties of the film. The pattern stoichiometry is characterized using microscopy with chemical and structural sensitivity, while XMCD-PEEM at the Co L-edge probes the magnetic state of the sample before and after irradiation. As will be discussed, the approach adopted provides local control on the film MA at the mesoscopic level, resulting in sharp out of plane magnetic domains in the sub-micron size range.
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