Christoph Schmidt

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• Colloidal domain lithography for regularly arranged artificial magnetic out-of-plane monodomains in Au/Co/Au layers.

  Authors: Piotr Kuświk, Arno Ehresmann, Maria Tekielak, Bogdan Szymański, Iosif Sveklo, Piotr Mazalski, Dieter Engel, Jan Kisielewski, Daniel Lengemann, Maciej Urbaniak, Christoph Schmidt, Andrzej Maziewski, Feliks Stobiecki

  Nanotechnology. 22(9):095302.

  Regularly arranged magnetic out-of-plane patterns in continuous and flat films are promising for applications in data storage technology (bit patterned media) or transport of individual magneticRegularly arranged magnetic out-of-plane patterns in continuous and flat films are promising for applications in data storage technology (bit patterned media) or transport of individual magnetic particles. Whereas topographic magnetic structures are fabricated by standard lithographical techniques, the fabrication of regularly arranged artificial domains in topographically flat films is difficult, since the free energy minimization determines the existence, shape, and regularity of domains. Here we show that keV He(+) ion bombardment of Au/Co/Au layer systems through a colloidal mask of hexagonally arranged spherical polystyrene beads enables magnetic patterning of regularly arranged cylindrical magnetic monodomains with out-of-plane magnetization embedded in a ferromagnetic matrix with easy-plane anisotropy. This colloidal domain lithography creates artificial domains via periodic lateral anisotropy variations induced by periodic defect density modulations. Magnetization reversal of the layer system observed by magnetic force microscopy shows individual disc switching indicating monodomain states.

• Thermal exchange bias field drifts after 10 keV He ion bombardment: Storage temperature dependence and initial number of coupling sites

  Authors: Christoph Schmidt, Tanja Weis, Dieter Engel, Arno Ehresmann

  Journal of Applied Physics. 110(11):113911.

• Thermal exchange bias field drift in field cooled Mn83Ir17/Co70Fe30 thin films after 10 keV-He ion bombardment

  Authors: Arno Ehresmann, Christoph Schmidt, Tanja Weis, Dieter Engel

  J. Appl. Phys. 109:023910.

  The thermal exchange bias field drift of sputter deposited Mn83Ir17(15 nm)/Co70Fe30(10 nm)/Ta thin films at room temperature after 10 keV He+ ion bombardment in an externally applied in-planeThe thermal exchange bias field drift of sputter deposited Mn83Ir17(15 nm)/Co70Fe30(10 nm)/Ta thin films at room temperature after 10 keV He+ ion bombardment in an externally applied in-plane magnetic field for different ion fluences was studied. Although field cooling of the layer system resulted in a temporally stable exchange bias field at room temperature the exchange bias field starts to drift after ion bombardment like in non-annealed samples. Between 1 and 648 h after ion bombardment a logarithmic increase in the absolute magnitude of the exchange bias field is observed. A tentative model is presented for its description based on noninteracting domains in the antiferromagnet. A comparison between experimental data and the model reveals the delicate interplay between the ion bombardment modified average antiferromagnetic anisotropy constants, exchange coupling constants, and relaxation time distributions in the polycrystalline layer system influencing the thermal drift velocities.

• Interface morphologies and magnetization characteristics of Co70Fe30 thin films deposited on conjugated polymer thin films

  Authors: Tobat P.I. Saragi, Christoph Schmidt, Karin Schultz, Tanja Weis, Josef Salbeck, Arno Ehresmann

  Journal of Magnetism and Magnetic Materials. 321:2204.