Unlocking of remanent magnetization of pole heads by medium stray fields0

摘要

We report investigations of a stochastic phenomenon in which pole heads used for perpendicular ' recording stay magnetized after the driving current is switched off. This remanent magnetization causes erasure of the information previously written on the disk. The length of the erasure was found to be in the range of several μs up to a few ms. Surprisingly it is found that the remanent magnetization state can be reduced by magnetization patterns that already exist on the disk at the time of writing. Experimental evidence is presented which illustrates that the unlocking of the remanent state can be influenced by the type and location of these magnetization patterns. It is concluded that magnetization patterns creating rotating fields are most efficient in destroying these remanent states.