Magnetic Force Microscopy

Magnetic force microscopy (MFM)

Magnetic properties of materials give rise to many applications in scientific and technological fields. The development of magnetic thin films has been of prime importance for spintronics and magnetic storage. This field is still booming and needs dedicated analysis set-ups. Near field force microscopy applied to magnetism has appeared as a simple way to measure magnetic forces on surfaces.

A Magnetic Force Microscope is an atomic force microscope with a magnetic tip (usually in CoCr). To the usual atomic force due to the electronic orbital hybridation is added the magnetic force, which is predominant at some distance of the surface (decreases more slowly than electronic forces with distance). Whereas the interaction range of the electronic forces are some nm, that of the magnetic force is some tens of nm.

The MFM images give information on the magnetic domains (lateral resolution: 10-100nm) and on any phenomenon inducing a magnetic field variation on the surface.

Example of image showing the magnetic domains at the surface of a FePt film magnetically nanostructured using selective irradiation. Non irradiated zones have a perpendicular anisotropy and present labyrinthic domains whereas irradiated zones have a planar anisotropy and present slight magnetic contrasts due to magnetic domain walls between in plane closing domains.

Recently the DMONS acquired a low temperature (LT) atomic force microscope (AttoAFMI from AttoCube) which is able to image and measure local characteristics of surfaces under an applied high magnetic field (<10T) and at low temperature (1.5K). The IPCMS is a rare French laboratory equipped with such an experimental setup.

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