Room Temperature Scanning Micro-Hall Probe Microscope Imaging of Ferromagnetic Microstructures Under Large Pulsed Magnetic Fields Generated by an Integrated Mini-Coil

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A fundamental understanding of the behavior of magnetic domains in external magnetic fields is important for the development of information technology such as ultra-high density magnetic recording media, high coercivity permanent magnets and multilayered ferromagnetic structures used for fabricating novel 'spintronic' devices.In this research, a unique magnetic imaging system comprising of a room temperature scanning Hall probe microscope with an integrated mini-coil capable of generating pulsed magnetic fields up to 3 Tesla (width of 3.5ms) was developed for the direct and non-invasive magnetic imaging of ferromagnetic micro-domains in the presence of extremely large external pulsed magnetic fields without adverse vibrational disturbance of the sample during measurements. The system was successfully used for magnetic imaging of the erasure process of bit patterns on the surface of 1.4MB written floppy disks and the dynamics of micro-domain structures of demagnetized strontium ferrite permanent magnets under large external pulsed magnetic fields.The combined mini-coil/RT-SHPM system was demonstrated to be a valuable instrument for the direct, quantitative and non-invasive observation of localized stray magnetic fields at the surfaces of magnetic recording media and ferromagnetic materials in the presence large external bias fields.