Berlin 2012 – scientific programme

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MA: Fachverband Magnetismus

MA 47: Micro- and Nanostructured Magnetic Materials II

MA 47.6: Talk

Thursday, March 29, 2012, 18:30–18:45, EB 202

Magnetization reversal in dipolarly coupled PdFe nanodot arrays — •Melanie Ewerlin, Derya Demirbas, Frank Brüssing, Oleg Petracic, and Hartmut Zabel — Institut für Experimentalphysik/Festkörperphysik, Ruhr-Universität Bochum, 44780 Bochum, Germany

We have studied a 2-dimensional XY macrospin model system by fabricating nanodot arrays from Pd1-xFex with low Fe-concentrations as magnetic material. Pd1-xFex films of 10 nm thickness and various Fe concentrations x were deposited by ion beam sputtering. Structural as well as magnetic characterizations were performed using superconducting quantum interference device (SQUID) magnetometry, magneto-optic Kerr effect (MOKE), atomic force microscopy (AFM) and x-ray diffraction (XRD). For the nanostructuring we used films with x=13 at% showing a Curie temperature of 290 K to ensure that the system can be cooled from a completely paramagnetic state into the macrospin state. We have fabricated circular dots with a diameter of 150 nm showing a single domain state. The dots are arranged on a square lattice with various inter-dot distances. The magnetization reversal of the entire system was studied using a low-temperature MOKE setup and compared to model expectations of a XY system with dipolar interactions. The results indicate a two step ordering process from intra-island to inter-island with decreasing temperature. To this end micromagnetic simulations are performed to determine the magnetization configuration of the dots depending on their thickness, diameter and distances.