Micro-Hall magnetometry is a sensitive technique to investigate the magnetic properties of individual micro- and nanostructures. In general, a Hall sensor is a thin semiconductor-based device in which a longitudinal current is applied and transverse Hall voltage is detected which measure the perpendicular magnetic stray field. Our micro-scaled Hall sensor applies a GaAs/AlGaAs heterostructures with 2DEG in the active sensor area and it is usually applied at T < 100 K in the ballisic regime of the sensor. This has been used, e.g., in order to study the magnetization switching of an individual Fe-filled carbon nanotubes (see figures).
Left: SEM image of an iron-filled carbon nanotubes placed on the 800 nm x 800 nm sized active area of a micro-Hall cross. Right: Hysteresis loop of the individual nanowire upon application of an external magnetic field.
An individual iron nanowire-filled carbon nanotube probed by micro-Hall magnetometry
K. Lipert, S. Bahr, F. Wolny, P. Atkinson, U. Weißker, T. Mühl, O.G. Schmidt, B. Büchner, R. Klingeler, Appl. Phys. Lett. 97, 212503 (2010)
Development of a Micro-Hall-Magnetometer and Studies on Individual Fe-filled Carbon Nanotubes
Kamil Lipert, PhD thesis, U Heidelberg 2011