Abstract
Using the magneto-optic Kerr effect and atomic force microscopy (AFM) we investigate nanoscale ferromagnetic entities directly patterned in thin superparamagnetic films of Fe-Cr by means of interfering laser beams. We demonstrate, for the first time, that a contact mode of AFM with a non-magnetic tip can be suitably modified to visualize in great detail the response to external fields of even a single nano-ferromagnetic entity in a patterned array. This new approach for magnetic imaging, which we consider to be a magnetostrictive response (MSR) technique, having a lateral resolution typical of AFM, is used to show the strong dependence of the magnetic response of these nanoscale entities to prior magnetization direction. The observed MSR effects provide further insight into the magnetic microstructural aspects of the laser patterned entities and explains qualitatively the information obtained by means of Kerr magnetometry and magnetic force microscopy.
