Ferromagnetic Co-C nanodot arrays produced by direct interferometric laser annealing

Magnetic properties of Co-C nanodot arrays produced by direct interferometric laser annealing are investigated by magnetic force microscopy (MFM) and magnetization measurements. The dots are formed by locally annealing sputtered amorphous Co-C films in regions where the laser intensity is highest. As-sputtered Co-C films do not exhibit ferromagnetic order at room temperature, but MFM shows that the dots become magnetic upon annealing, possibly due to the agglomeration or phase separation of Co-rich clusters. The dots are embedded in either a paramagnetic or weakly magnetic matrix. The magnetic properties of the generated pattern can be changed by varying the laser power. The present results show that direct interferometric lithography may become a useful tool for fabricating future patterned magnetic nanostructures