Detection of In-Plane Magnetized Grains With a Magnetoresistive Head

Magnesium oxide (MgO) is an important component in heat-assisted magnetic recording (HAMR) media, serving as an excellent seed layer for perpendicular orientation of FePt grains. However, it is difficult to detect the in-plane magnetic grains caused by the MgO boundaries. This work uses micromagnetic simulation to study the detection of longitudinally magnetized grains in FePt-based HAMR media using a novel 45° magnetoresistive read head design. By leveraging the reduced in-plane anisotropy of FePt grains and the magnetostatic field generated by adjacent tracks, an asymmetric magnetization distribution is induced along the cross-track direction. This asymmetry facilitates the detection of in-plane magnetization components using playback signals obtained from micromagnetic simulations. The method effectively identifies noise sources, thus providing a cost-efficient alternative to other experimental techniques.