Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 2: Micro and Nanostructured Magnetic Materials I

MA 2.2: Vortrag

Montag, 25. Februar 2008, 10:30–10:45, EB 301

Micro-Hall-Magnetometry for the investigation of magnetic nanoparticles — •Bastian Büttner, Florian Lochner, Christoph Brüne, Charles Gould, Georg Schmidt, and Laurens W. Molenkamp — Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, 97074 Würzburg, Germany

Nanoscale ferromagnetic thin films and particles are of great interest for spintronic applications. The non-volatility offers capabilities for data storage and novel electronic devices. Micro-Hall-Magnetometry is known as a simple, reliable and highly sensitive measurement method which is capable of investigating the magnetization of individual nanoscale particles over a wide temperature range [1]. Here we present the fabrication and comparison of micro-Hall bars in different material systems, namely InAs, HgTe, and (Al,Ga)As. In order to achieve high sensitivity for single, isolated nanoparticles it is essential to decrease the dimensions of the Hall cross to a size where crystal defects and sidewall depletion become an important factor; we have developed various different designs to mitigate these effects. The micro-Hall bars have been characterized using lithographically defined metallic nanomagnets. As an application, we want to use the micro-Hall bars to characterize chemically synthesized randomly orientated nanoparticles. We additionally developed a process which allows for exact positioning and aligning the Hall bar without damaging the nanoparticle. We will present details of the processing and experimental results.
[1] A. K. Geim et al., Appl. Phys. Lett. 71, 2379 (1997)