Regensburg 2013 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 12: Poster 1

DF 12.28: Poster

Tuesday, March 12, 2013, 10:30–13:30, Poster D

Measurement of magnetic moment distribution of ferrofluids with single nanoparticle resolution using atomic force microscopy — •Stephan Block¹ and Christiane A. Helm² — ¹ZIK HIKE, Fleischmannstr. 42 - 44, D-17475 Greifswald, Germany — ²Institut für Physik, Ernst-Moritz-Arndt Universität, Felix-Hausdorff-Str. 6, D-17487 Greifswald, Germany

An atomic force microscopy (AFM) method is presented, which allows the simultaneous measurement of magnetic and geometric properties of nm-sized objects (nanoparticles, e.g. colloids or clusters). An oscillating magnetic field is applied to the sample and the surface magnetization is probed using a magnetic AFM-tip. Spatial changes of the magnetic flux density affect the vibration amplitude of the tip and thus, (dynamic) magnetic properties of the surface can be determined with a lateral resolution of few nanometers. The principles of the experimental setup and the data analysis are outlined. It is shown that the resolution is sufficiently high to resolve magnetic moments of single superparamagnetic maghemite nanoparticles (diameter > 4 nm). The approach is applied to determine the distribution of magnetic moments in different ferrofluids on a single particle level.