Scanning Hall probe microscopy
Various techniques have been developed to investigate the surface magnetic structure of materials. One possible observation technique is scanning Hall probe microscopy which has been shown to be a very sensitive, noninvasive instrument allowing to obtain the quantitative measurement of surface magnetic field profiles with high spatial resolution below 1 µm.
Our low noise scanning Hall probe microscope has a field resolution into the sub Oe range. The microscope incorporates a Hall probe which is brought into close proximity with the sample surface using scanning tunneling microscopy STM positioning techniques. The Hall probe is tilted approx. 1° with respect to the sample. The sample is usually first approached until tunneling is established and then the Hall probe is scanned across the surface to measure the magnetic field and the surface topography simultaneously. Alternatively the sample can be retracted and the 3D surface magnetic field distribution can be obtained.
Hall probe microscopy images obtained in STM and retracted mode, respectively (top images, width 50 µm). Detail of the STM mode pictures in "artistic" 3D representation (bottom).