Investigation of Microscopic Demagnetization Process Using Magneto-Optical Microscopy.

Detailed demagnetization process depending on various external field profiles has been investigated using a magneto-optical Kerr/Faraday microscopy for a Co/Pt multilayer film with a perpendicular magnetic anisotropy. By quantitatively analyzing local magnetic domain structures, we propose that it is possible to define a parameter $\eta$ , which represents how well the demagnetization has been carried out microscopically. The degree of demagnetization $\eta$ , defined by a ratio between the final demagnetized image intensity and saturated image intensity, has been experimentally found to significantly reflect the microscopic demagnetization behavior. Dependences of $\eta$ on the maximum amplitude, decreased step size, and effective sweeping rate of alternating demagnetizing field have been systematically investigated together with a direct microscopic observation of magnetic domain structures. [ABSTRACT FROM AUTHOR]