Magnetic interactions in FePt∕soft magnetic underlayer double-layered structure observed by anomalous Hall effect

Abstract

The effect of magnetic interactions between an FePt recording layer with perpendicular magnetic anisotropy and a soft magnetic layer of FeCoB (or NiFe) was investigated using the anomalous Hall voltage measurement method. The nucleation field and the slope around the coercivity of the Hall hysteresis loop revealed by the recording layer were found to significantly decrease depending on the type of interface. The coercivity corresponding to the in-plane magnetization components of the soft magnetic layer was found to increase while coexisting with an FePt layer.

Recording media research for future hard disk drives

“…While magneto-optical methods such as MOKE are able to evaluate double-layered perpendicular media with thick RL and IL, these will also face problems for ultra-thin media films of the future due to the penetration of the incident laser deep down into the SUL. In this regard, alternative techniques that make use of the ferromagnetic or anomalous Hall effect (AHE) have been found to be effective in separating and evaluating the properties of the RL and the SUL [74,75]. This is possible due to the difference in symmetry of the contributions from the perpendicular RL moment and the in-plane SUL moment.…”

An approach to understand the effect of interlayer coupling in composite media using anomalous Hall effect measurement

“…Application of anomalous Hall effect ͑AHE͒ measurement could be a possible means of realizing such probing, which is due to its strong dependence on layer thickness, film composition, and spin orientation. [3][4][5] In this study, in order to get a better insight about interlayer coupling the AHE method was applied on a composite structure comprised of a Co-Cr-Pt-SiO 2 ͑CCPS layer͒ and a Co-Cr-Pt ͑CCP͒ layer, where the CCP with comparatively low K u assists in the magnetization reversal in the granulartype CCPS layer with high K u .…”