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

摘要

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 x 0.8μm~2; room temperature Hall coefficient of 0.3Q/G) exhibiting extremely high magnetic field sensitivity (0.04G/√Hz) 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.