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MA: Fachverband Magnetismus
MA 19: Poster I (Bio- and Molecular Magnetism/ Magnetic Particles and Clusters/ Micro- and Nanostructured Magnetic Materials/ Magnetic Materials/ Multiferroics/ Magnetic Shape Memory Alloys/ Electron Theory of Magntism/ Spincaloric Transport/ Magnetic Coupling and Exchange Bias/ Magnetization Dynamics/ Micromagnetism and Computational Magnetics)
MA 19.8: Poster
Tuesday, March 15, 2011, 10:45–13:00, P2
Transition from superparamagnetism to correlated ferromagnetism in Pt capped Co nanoparticles — •Astrid Ebbing1, Leonardo Agudo2, Gunther Eggeler2, and Oleg Petracic1 — 1Institut für Experimentalphysik/Festkörperphysik, Ruhr-Universität Bochum, 44780 Bochum — 2Institut für Werkstoffe, Ruhr-Universität Bochum, 44780 Bochum
In this work we show that by capping Co nanoparticles with small amounts of Pt drastic changes of the magnetic properties can be induced. The magnetic properties were investigated using superconducting quantum interference device (SQUID) magnetometry. We find that for zero and for very small amounts of Pt (nominal thickness t(Pt) < 0.7 nm) the nanoparticles behave superparamagnetic. With increasing t(Pt) the blocking temperature is enhanced from 15 K up to 110 K. However, for values t(Pt) > 1 nm a strongly coupled state is encountered resembling a ferromagnet with T_c values > 300 K.