The role of MFM signal in mark size measurement in probe-based magnetic recording on CoNi/Pt multilayers

A method of heat-assisted magnetic recording (HAMR) potentially suitable for probe-based storage systems is characterized. Magnetic marks were formed by a scanning tunneling microscopy (STM)-based thermal magnetic mechanism on a perpendicular CoNi/Pt multilayered film. Magnetic force microscopy (MFM) was applied to display those marks. The MFM signal is dependent of the lift-height during MFM scanning: smaller lift-height leads to higher resolution of the MFM image and a double-peak signal line, while higher lift-height leads to lower resolution and a single-peak signal line. Theoretical calculation of the magnetic field from the mark was executed. It agrees well with experiments, and demonstrates the method of mark size measurement in perpendicular media: full-width half-maximum (FWHM) of the measured MFM signal.