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Room temperature magnetic imaging of magnetic storage media and garnet epilayers in the presence of external magnetic fields using a sub-micron GaAs SHPM

SANDHU, Adarsh
MASUDA, Hiroshi
Oral, Ahmet
Bending, Simon.J.
A multipurpose room temperature scanning Hall probe microscope (RT-SHPM) system incorporating an ultra-high sensitive sub-micron GaAs Hall probe (active area of 0.8 0.8 mm2 ; room temperature Hall coefficient of 0.3 O/G) exhibiting extremely high magneticfield sensitivity (0.04G/pHz) was used for the direct, non-invasive and quantitative imaging of magnetic field fluctuations in very close proximity to the surfaces of thin film magnetic storage media, Bi substituted iron garnet epilayers and demagnetized Sr-ferrite permanent magnets placed in external magnetic fields. A scanning tunnelling microscope tip integrated adjacent to the Hall probe was used for precise vertical positioning of the probe. RT-SHPM images of 1.4 MB written floppy disks clearly showed well-defined magnetic transitions to coalesce into small island-like structures under external perpendicular fields greater than 1300 Oe. The RT-SHPM is demonstrated to be a versatile means of quantitatively monitoring micron-sized magnetic domain structures in the presence of external magnetic fields at room temperature