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PV: Plenarvorträge

PV VIII

PV VIII: Plenary Talk

Wednesday, March 29, 2006, 08:30–09:15, HSZ 01

Imaging and magnetic characterization of individual nanostructures in a transmission electron microscope (TEM) — •Josef Zweck, Thomas Uhlig, and Martin Heumann — NWF II - Physik der Universität Regensburg, D-93040 Regensburg, FRG

Magnetic materials are increasingly used for modern devices (sensors, memories, switches etc.) because of their simplicity of operation. These devices promise to be small, fast, cheap and - when used for memories - non-volatile. Then, the question arises whether magnetism in small volumina does still behave the same way as in bulk material. To answer this question, a method is needed which allows to probe each one of these particles individually for their magnetic properties and to be able to in-situ manipulate its state. One of the few techniques capable to do this is Lorentz electron microscopy. Methods and possibilities of modern Lorentz microscopy to measure magnetic properties of patterned materials will be demonstrated. Besides the conventional Fresnel imaging technique, the more advanced techniques of differential phase contrast imaging (DPC) and electron holography are introduced The examples given include a new magnetic ground state, the measurement of hysteresis loops of individual particles, the trapping of magnetic vortices in holes and anisotropy traps as well as thermally assisted switching of pure single domain particles.