Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 91: [MA] Poster II

O 91.29: Poster

Friday, March 30, 2012, 11:00–14:00, Poster A

Investigation of the influence of dipolar interactions on the magnetic behavior of Ni nanorods — •Florian Krämer, Philipp Bender, Andreas Tschöpe, and Rainer Birringer — Universität des Saarlandes, Saarbrücken

Ni nanorods with diameters < 42nm are expected to be uniaxial ferromagnetic single domain particles. In recent years, the magnetic properties of Ni nanorods in porous alumina templates were extensively studied. However, the investigation of characteristic magnetic properties was hampered by the large dipolar interactions (DI) due to the dense packing of the rods in the template. We synthesized Ni nanorods (D =19 nm) by current-pulsed electrodeposition of Ni into ordered porous alumina templates. The filled templates were characterized by static magnetization measurements (SMM) as a modelsystem of uniaxial ferromagnets with significant DI. Then, the nanorods were released from the templates by dissolution of the alumina in aqueous NaOH, dispersed in 20 wt% gelatine solutions @60^∘C and aligned paralell by an external homogenous magnetic field during gelation. These gels were also characterized by SMM as an corresponding system of uniaxial ferromagnets with negligible DI. The objective of this work was to study the influence of DI on the magnetic properties of such uniaxial ferromagnetic particles. We measured the remanence and the coercivity as a function of the angle between the rodaxis and the external field, the switching field distribution, the shape anisotropy constant and the activation volume.