Dresden 2011 – scientific programme

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KR: Fachgruppe Kristallographie

KR 5: Poster Multiferroics (Joint Session of MA, DF, DS, KR, TT)

KR 5.12: Poster

Tuesday, March 15, 2011, 10:45–13:00, P2

AFM-based method for imaging and magnetic characterization of isolated nanoparticles with nanometer lateral resolution — •Stephan Block and Christiane A. Helm — Institut für Physik, Ernst-Moritz-Arndt Universität, Felix-Hausdorff-Str. 6, D-17489 Greifswald, Germany

We present a new AFM-based method, which allows the simultaneous measurement of magnetic and spatial properties of nm-sized objects (nanoparticles, e.g. colloids or clusters). Thus, it becomes possible to distinguish different materials by their unique magnetism (e.g. superparamagnetism or diamagnetism). Basically, an oscillating magnetic field is applied to the sample and with a magnetic AFM-tip the surface magnetization is probed. 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 high resolution.

In the present work, this new technique is applied to (diamagnetic) gold and (superparamagnetic) iron-(II,III)-oxide nanoparticles. It is shown, that the magnetic susceptibility of nanoparticles with lateral resolution of few nanometers can be resolved at least qualitatively. Additionally, the preliminary measurements show that these nanoparticles (with a diameter of less than 20 nm) can be clearly distinguished by this new method. This allows us to unambiguously identify nanoparticles in AFM measurements simply by the nature of their magnetism, which might be a very valuable tool in biochemical or biomedical methods like AFM-based immunolabeling of proteins.