Nanomagnetism: High-resolution magnetic surface studies using spin polarization of secondary electrons (invited) (abstract)

Abstract

Intense scientific curiosity and the drive to increase information storage density have fueled extensive theoretical and experimental work on magnetic surfaces. Symmetry and bonding are reduced at surfaces and in magnetic materials this can cause changes in the moment and magnetic anisotropy over distances too small to probe optically. We have constructed and used a thin-film, spin-orbit scattering polarimeter (based on the NBS design) to measure the polarization of secondary electrons excited from magnetic surfaces. The low-energy secondary electrons come from the outermost atomic layers and carry a polarization proportional to valence polarization of the elements in the surface. Results on amorphous cobalt base alloys indicate a surface anisotropy in the outermost 2–5 nm pulling the magnetization away from the bulk preferred direction. High lateral resolution can be achieved by using the thin-film polarimeter to measure the polarization of secondary electrons excited from a magnetic surface by a high-resolution (25 Å), field-emission source, scanning electron microscope.