Morphological and magnetic analysis of Fe nanostructures on W(110) by using scanning tunneling microscopy and Lorentz microscopy

We investigated morphological features and magnetic properties of epitaxial Fe nanostructures (films, stripes and nanoparticles) on a W(110) surface with monoatomic steps preferentially along the direction. The nanostructures were prepared in ultra-high vacuum by using electron-beam evaporation and subsequent annealing at different temperatures. Scanning tunneling microscopy measurements in-situ revealed elongated Fe nanostructures with aspect ratios of up to . The observable shape and orientation (along or perpendicular to the monoatomic steps of the substrate) of the nanostructures depended substantially on the preparation parameters. By capping the system with 7 monolayers of Pt, the magnetic properties of selected Fe nanostructures could be analyzed ex-situ using Lorentz microscopy revealing diversified results. Depending on the size and shape, different magnetization structures, such as single domain, two domains and vortex, were observed. A precise intensity profile analysis demonstrated that the magnetic field values of different magnetic structures are close to each other and equal 2.4 T.