Imaging Perpendicular Magnetic Domains in Plan-view Using Lorentz Transmission Electron Microscopy

The study of magnetic materials requires an understanding of not only their magnetic properties, but also their microstructure. Transmission electron microscopy (TEM) is a powerful characterization instrument because of its ability to provide both microstructural and magnetic information. In TEM, electrons can be deflected by a Lorentz force created by a magnetic field from a magnetic material. This deflection can then be detected by electron holography [1] or the Fresnel Lorentz imaging technique [2]. In this report, we present the results of applying the latter technique with a novel use of the plan-view orientation to observe perpendicularly magnetized domains in thin film media used in hard disk drives. The results show that in this orientation, for which the electron beam is parallel to the dominant magnetic fields in the sample, the TEM can be effectively used to obtain information about the magnetic domains (i.e. the recording bits).