Electron holography has revealed dipolar ferromagnetic domain structures in ordered monolayer arrays of Co nanoparticles. In zero-field-cooling experiments, we demonstrate the formation of micron-sized magnetically ordered regions with transverse domain walls, and a spatially varying moment order parameter. Truncated vortex structures that can be modified by an applied field are observed near the sample edges. The collectively magnetized state shows soft magnetic properties and long-range order that is stable over times over 1 h at 108 K.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)