Berlin 2015 – scientific programme

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MA: Fachverband Magnetismus

MA 49: POSTER II

MA 49.18: Poster

Thursday, March 19, 2015, 15:00–18:00, Poster A

Fabrication and characterization of micro-Hall-Magnetometers for high-resolution local magnetic induction measurements — •Maryam Akbari, Merlin Pohlit, and Jens Müller — Physikalisches Institut, Goethe-Universität, Frankfurt (M), Germany

Micro-Hall magnetometry is an ultra-sensitive tool for studying the magnetic properties of individual micro- and nanostructures by detecting their magnetic stray field. To that end the samples are positioned onto the surface of a homebuilt sensor, where a series of adjacent lithographically-defined Hall crosses allows for spatially-resolved measurements with micron-size resolution. The technique is based on a sensor element made from a high-mobility two-dimensional electron gas (2DEG) in a GaAs/AlGaAs heterostructure. The main aspect of the presented work is to investigate the suitablility of a more advanced 2DEG wafer material, e.g., in terms of a shallower 2DEG to further increase the sensitivity by minimizing the sample to sensor distance. It is important to characterize the wafer material's transport properties (e.g. charge-carrier density, electron mobility) and, in particular, it is noise behavior by performing fluctuation spectroscopy. Additionally the versatility of the magnetometers is demonstrated by various measuring techniques including eight-terminal Hall gradiometry and, as a new application, FORC-measurements (first order reversal curves) for investigating interaction effect in ensembles of nano magnets.