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Dresden 2009 – scientific programme

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MA: Fachverband Magnetismus

MA 36: Magnetic Particles and Clusters II

MA 36.4: Talk

Thursday, March 26, 2009, 16:00–16:15, HSZ 401

Decoupling of the surface and core magnetic contribution in antiferromagnetic nanostructures — •Maria Jose Benitez1,2, Oleg Petracic1, Harun Tüysüz2, Florin Radu3, Ferdi Schüth2, and Hartmut Zabel11Institut für Experimentalphysik/Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum — 2Max-Planck Institut für Kohlenforschung, D-45470 Mülheim an der Ruhr — 3BESSY GmbH, Albert-Einstein Strasse 15, D-12489 Berlin

Ferromagnetic particles enter superparamagnetism upon decreasing their size. However, antiferromagnetic nanoparticles are governed by core-shell behavior. We present a systematic magnetometry study on antiferromagnetic Co3O4 and CoO nanowires with various structure sizes between 5 and 10nm. We identify two different magnetic contributions, viz. one being governed by the antiferromagnetically ordered wire cores. The second one is attributed to the antiferromagnetic surface. We demonstrate that the surface behaves as a two-dimensional diluted antiferromagnet in a field (DAFF) [1]. Furthermore we show that measurements of the thermoremanent (TRM) and isothermoremanent magnetization (IRM) can serve as a magnetic fingerprint of particularly the surface contribution to the magnetization.

[1] M. J. Benitez et al., Phys. Rev. Lett. 101, 097206 (2008).

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