Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 16: Micro- and Nanostructured Magnetic Materials II

MA 16.6: Vortrag

Mittwoch, 24. März 2010, 11:30–11:45, H23

Two distinct magnetic switching events in core-shell nanowires with fully controlled geometric parameters — Yuen Tung Chong, Detlef Görlitz, Stefan Martens, Kornelius Nielsch, and •Julien Bachmann — Institut für Angewandte Physik, Universität Hamburg

A preparative strategy that combines atomic layer deposition (ALD) with electrodeposition in a porous template (anodic alumina) enables one to arrange a nickel core with an iron oxide shell coaxially in biphasic magnetic nanowires. The wires have large aspect ratios (>100), they are ordered in parallel arrays, and in each of them, a non-magnetic silica spacer layer physically separates core from shell. The thickness of each layer is adjustable between 3 and 30 nm or so, thus, given a fixed outer diameter of 150 nm, the core diameter may be varied between approximately 50 and 100 nm.

In the presence of a sufficiently thick non-magnetic spacer, core and shell revert their magnetization separately from each other, and the switching fields are determined mostly by the respective geometric parameters. The two distinct reversal events are characterized by magnetometric measurements on the ensembles: the hysteresis loops strongly depend on systematic changes in geometry and temperature.