Magnetic force microscopy analysis of thermal stability in longitudinal media

The thermal stability of written bits in high density longitudinal recording media is investigated using magnetic force microscopy (MFM). The time dependence of the MFM signal is examined for different linear densities on CoCrPt-based media of various thickness. At ambient temperature, lesser decay is observed using the MFM compared to spin stand measurements on the same CoCrPtTaNb media on Al which emphasizes the dependence of bit stability with writing conditions. Moderate anneals at 373 K reveal a rapid initial similar to 10% signal decay followed by stable behavior not observed in the magnetization time dependence measurements. 200 kfci tracks on a 20-nm thick CoCrPtTa medium on Si with a coercivity of 3 kOe displayed stable (similar to 2%) behavior against a 105-hour anneal at 373 K in air. These results are correlated with media properties to obtain parameters that are good indicators of thermal stability performance.