Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 10: Poster I

MA 10.31: Poster

Dienstag, 23. März 2010, 10:45–13:45, Poster A

Investigation of exchange bias field of NiMn pinned Co nanoparticles — •Balati Kuerbanjiang, Benjamin Riedmüller, and Ulrich Herr — Institut für Mikro- und Nanomaterialien, Universität Ulm, 89081, Ulm, Germany

Co nanoparticles deposited on a sputtered NiMn layer have been studied for the purpose of the exchange bias field. About 30 nm of NiMn layer was deposited on Si substrate by magnetron sputtering, then Co nanoparticles were deposited in situ on the NiMn layer using inert gas condensation technique. Samples were subsequently covered by about 5 nm of Cu in order to prevent oxidation of particles in air. Chemical states and compositions of the samples were examined by XPS inside the UHV system. Ex situ annealing has been carried out to achieve the antiferromagnetic NiMn phase at 350 °C for 10 min, in an applied field of 350 Oe. Annealing was performed under vacuum to avoid degradation of the magnetic properties. The phase transformation of the NiMn was investigated by X-ray diffraction. The size and the coverage of Co nanoparticles has been determined by AFM and SEM. The influence of the magnetic interaction between NiMn AFM layer and the FM Co particles of different sizes and densities was studied using vibrating sample magnetometry (VSM), magneto-optical Kerr effect (MOKE) and magnetic force microscopy (MFM).