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Berlin 2008 – scientific programme

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MA: Fachverband Magnetismus

MA 18: Poster I : Bio Magn. (1-2); Mag.Imgaging (3-9); Magn. Semiconductors (10-16); Half Metals & Oxides (17-20); Coupl.Phenomena (21-27); Magn. Mat. (28-41); Micro & Nanostr. Magn. Materials (42-61); Micro Magn. (62-64); Surface Magnetism (65-70); Transport Phenomena (71-85)

MA 18.48: Poster

Tuesday, February 26, 2008, 15:15–18:30, Poster E

Understanding the behaviour of mesoporous Co3O4 using TRM-IRM curves as fingerprints of magnetic systems — •María José Benítez Romero1, Oleg Petracic1, Yuriy Yanson1, Elena Lorena Salabas2, Ferdi Schüth2, and Hartmut Zabel11Institut für Experimentalphysik/Festkörperphysik, Ruhr-Universität, Bochum, Germany — 2Max-Planck Institut für Kohlenforschung, Mülheim an der Ruhr, Germany

Antiferromagnetic mesoporous Co3O4 exhibits interesting magnetic properties at low temperatures: bifurcation of the FC and ZFC susceptibilities at 30 K and shifted hysteresis loops after field cooling. This anomalous behavior originates due to the exchange interaction between the AFM core and the surface spins. To understand the nature of the surface spins in the nanostructured Co3O4 we propose to study the thermoremanent magnetization (TRM) and isothermal remanent magnetization (IRM) curves in this AFM as well as in other magnetic systems. The ordered mesoporous Co3O4 has been synthesized using the nanocasting method. The nanowires were characterized using X-ray diffraction, N2 adsorption-desorption isotherms, transmission electron microscopy and a superconducting quantum interference device magnetometer. We report measurements of thermoremanent moments and isothermal remanent moments in spin glass, exchange bias, superparamagnetic and antiferromagnetic systems. The analysis of thermal and isothermal remanence curves suggest that the mesoporous Co3O4 consists of antiferromagnetically aligned core spins and a spin-glass-like surface layer.

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