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Bilayers of high-temperature superconducting YBa2Cu3O 7−δ and amorphous soft-magnetic CoFeB have been prepared by pulsed-laser deposition and subsequent ion beam sputtering. In such structures magnetic coupling phenomena are found between the superconducting component and the ferromagnetic component. First, a significant increase of the critical current in the superconductor at temperatures close to Tc is found which is attributed to magnetic flux line pinning. Second, magnetic coupling across the interface allows a transfer of the current pattern of the superconductor into the ferromagnet via magnetic stray fields. This creates a map of the current flow of the superconductor inside the ferromagnet which is persistent when heating the bilayer up to room temperature. If it can be realized that the ferromagnet does not harm the superconductor too much, this could offer an easy (and novel) way of characterizing the current transport in superconductors.

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The magnetization reversal in nanoscaled antidot lattices is widely investigated to understand the tunability of the magnetic anisotropy and the coercive field through nanostructuring of thin films. By investigating highly ordered focused ion beam milled antidot lattices with a combination of first-order reversal curves and magnetic x-ray microscopy, we fully elucidate the magnetization reversal along the distinct orientations of a hexagonal antidot lattice. This combination proves especially powerful as all partial steps of this complex magnetization reversal can be identified and subsequently imaged. Through this approach we discovered several additional steps that were neglected in previous studies. Furthermore, by imaging the microscopic magnetization state during each reversal step, we were able to link the coercive and interaction fields determined by the first-order reversal curve method to true microscopic magnetization configurations and determine their origin.