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MA: Magnetismus

MA 20: Poster:Schichten(1-29),Spintrsp(30-45),Ex-Bias(46-63),Spindyn(64-75),Mikromat.(76-80),Cluster(81-94),Abbv.(95-99),Obflm(100-02),SpElek.(103-09),E-Theo(110-14),Mikromag.(115-16),Spin+PÜ(117-26),Mag.Mat.(127-51),Meth.(152-55),Mol.Mag(156-59),Kondo(160-65

MA 20.91: Poster

Montag, 7. März 2005, 14:00–18:00, Poster TU C

Magnetic property of a weakly interacting nanoparticle system — •Xi Chen¹, Subankar Bedanta¹, Wolfgang Kleemann¹, S. Cardoso², and P. P. Freitas² — ¹Angewandte Physik, Universität Duisburg-Essen, D-47048 Duisburg, Germany — ²INESC, Rua Alves Redol 9-1, 1000, Lisbon, Portugal

The magnetic property of a weakly interacting nanoparticle system [CoFe(0.7 nm)/Al₂O₃(3 nm)]₁₀ is investigated by a Superconducting Quantum Interference Device (SQUID) magnetometer. The temperature T dependence of the field cooled magnetization shows a clear increase at low temperature following a simple Curie law, which can be due to the “lost” spins undetectable in Transmission Electron Microscopy (TEM) images. The relaxation curves of the thermoremanent magnetic moment at different temperatures collapse onto one master curve under Tln(t/τ ₀) scaling. Aging and memory effects are also observed, which evidence a collective spin glass-like behavior in this nanoparticle system.