Regensburg 2010 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 9: Magnetic Particles, Clusters
MA 9.9: Vortrag
Montag, 22. März 2010, 17:15–17:30, H23
Manipulation of the magnetic properties of Co nanoparticles by Pt or Pd capping — •Astrid Ebbing1, Oleg Petracic1, Olav Hellwig2, Leonardo Agudo3, Gunther Eggeler3, and Hartmut Zabel1 — 1Experimentalphysik IV, Ruhr-Universität Bochum, 44780 Bochum — 2San Jose Research Center, Hitachi Global Storage Technologies, San Jose, California 95135, USA — 3Institute for Materials, Department of Materials Science, Ruhr-Universität Bochum, 44780 Bochum
We have prepared self-assembled Co nanoparticles with a diameter of approximately 3 nm by sputter-deposition on alumina buffer layers and investigated the effect of capping with different amounts of Pt or Pd. The magnetic properties have been studied using a superconducting quantum interference device (SQUID) magnetometer and magneto-optic Kerr effect as function of the nominal thickness of the capping material. Structural characterization has been performed by employing transmission electron microscopy (TEM) and atomic force microscopy (AFM). Co particles covered only by the Al2O3 protection layer show regular superparamagnetic behavior with a blocking temperature of TB = 22 K. However, the Pt or Pd cap layer strongly modifies the magnetic properties and shifts the blocking temperature to higher values. E.g. for a nominal Pt capping thickness of 0.7 nm the system becomes even ferromagnetic with a Curie temperature of approx. 487 K.