Unlocking of remanent magnetization of pole heads by "rumble strips"

Perpendicular recording generally uses a "single pole" head, which acts on a recording medium with a perpendicularly oriented storage layer and a magnetically soft underlayer (SUL). The role of the SUL is to enforce the write field and is an essential part of a perpendicular recording system. The pole geometry gives rise to new phenomena, which can cause severe problems for disk drive applications. One such effect is a delayed relaxation of the magnetization of the pole tip after information has been written. The permanently magnetized pole tip erases the magnetization pattern written on the disk and hence this effect has been termed "erase-after-write" (EAW). The present contribution deals with the investigation of EAW phenomena.