Spin-polarized low-energy electron microscopy study of the magnetic microstructure of ultra-thin epitaxial cobalt films on W(110)

Abstract

Magnetic domain formation in ultra-thin Co films on W(110) was studied with spin-polarized low-energy electron microscopy (SPLEEM). Films with the expected hexagonal structure were grown on the clean tungsten surface, but also fcc structured films with a (100) plane parallel to the surface could be prepared on a stabilizing tungsten carbide layer. Generally, fcc Co films showed very irregular in-plane magnetization between 3 and 11 ML thickness. We were able to record subtle changes in the magnetic domain structure with increasing film thickness. For films with hexagonal structure, first in-plane contrast was observed at 3 ML. Rotation of the substrate crystal established the presence of a uniaxial in-plane anisotropy with the easy axis along the W[1 1 0] direction for a 6 ML film.