Spin-Polarized Scanning Electron Microscopy

Abstract

Spin-polarized scanning electron microscopy (spin SEM) is a method to observe magnetic domain structures at a ferromagnetic sample surface. It is based on the phenomenon where the spin-polarization of the secondary electrons from a ferromagnetic sample is anti-parallel to the magnetization vector at the originating point of the secondary electrons. The spin-polarizations are analyzed while scanning the sample surface with a probe electron beam, which produces an image of the magnetic domain structure. This principle has afforded several excellent capabilities. The spatial resolution is better than 10 nm, and the method can produce magnetic domain images that are not affected by topography. Moreover, it can analyze not only magnetic domain shapes, but also magnetization directions in three-dimensional (3-D) space. Spin SEM has mainly been used in metal ferromagnetics or for magnetic devices such as recording media and permanent magnets, taking advantage of these characteristics. In this chapter, after the principle and the basic components of the instrument are explained, various spin-SEM results are introduced.