Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 40: Poster II: Bio- and Molecular Magnetism (1-9); Magnetic Coupling Phenomena/Exchange Bias (10-15); Magnetic Particlicles and Clusters (16-29); Micro and Nanostructured Magnetic Materials (30-51); Multiferroics (52-64); Spin Injection in Heterostructures (65-67); Spin-Dyn./Spin-Torque (68-93); Spindependent Transport (94-108)
MA 40.42: Poster
Freitag, 27. März 2009, 11:00–14:00, P1A
Magnetic viscosity in Co/Pt multilayers on nanospheres — •Cristina Bran1, Volker Neu1, Ulrike Wolff1, Till Ulbrich2, Manfred Albrecht3, and Ludwig Schultz1 — 1IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden, Germany — 2University of Konstanz, Department of Physics, D-78457 Konstanz, Germany — 3Institute of Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany
Magnetic nanoparticles have attracted considerable interest in recent years due to the possible applications in high density data storage technology. Requirements are a well defined and localized magnetic switching behavior and a large thermal stability in zero fields. The thermal stability of (Co/Pt)N multilayers with different numbers of repeats (N), deposited on nanospheres [1] is studied by magnetic viscosity measurements. For this, the time dependent magnetization decay is recorded at different reversal fields. The linear evolution of magnetization with ln(t) is interpreted as a relatively large energy barrier distribution. By measuring recoil loops we determine the irreversible susceptibility, which, together with viscosity data, allows to calculate the activation volume and to correlate these results to the magnetic particle volume. The results show that the activation volume is much smaller than the particle’s physical volume which indicates a non-uniform magnetic reversal within individual nanospheres. This finding is also a possible prerequisite for an individual particle switching expected from bit patterned media. [1] M. Albrecht et al, Nature Materials 4, 203 (2005).