Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 36: Magnetic Particles and Clusters II
MA 36.4: Vortrag
Donnerstag, 26. März 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 Zabel1 — 1Institut 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).