Magnetic domain observation in writer pole tip for perpendicular recording head by electron holography

Abstract

Electron holographic observations were performed in order to clarify the magnetic domain structures in nanosized pole tips for perpendicular recording heads made from Ni–Fe and Co–Ni–Fe. While an external magnetic field was applied, the magnetic fields leaking from the pole tips as well as the detailed magnetic flux distribution inside them were visualized for the first time. In addition, we report the direct observation result that implies the pole erasure characteristic of the Co–Ni–Fe pole tip. The observations have revealed that electron holography provides useful information for understanding the magnetic characteristics of nanosized pole tips for perpendicular recording heads.