  We demonstrate quantitative ballistic electron magnetic microscopy (BEMM)
imaging of simple model Fe(001) nanostructures. We use in situ nanostencil
shadow mask resistless patterning combined with molecular beam epitaxy
deposition to prepare under ultra-high vacuum conditions nanostructured
epitaxial Fe/Au/Fe/GaAs(001) spin-valves. In this epitaxial system, the
magnetization of the bottom Fe/GaAs(001) electrode is parallel to the [110]
direction, defining accurately the analysis direction for the BEMM experiments.
The large hot-electron magnetoresistance of the Fe/Au/Fe/GaAs(001) epitaxial
spin-valve allows us to image various stable magnetic configurations on the
as-grown Fe(001) microstructures with a high sensitivity, even for small
misalignments of both magnetic electrodes. The angular dependence of the
hot-electron magnetocurrent is used to convert magnetization maps calculated by
micromagnetic simulations into simulated BEMM images. The calculated BEMM
images and magnetization rotation profiles show quantitative agreement with
experiments and allow us to investigate the magnetic phase diagram of these
model Fe(001) microstructures. Finally, magnetic domain reversals are observed
under high current density pulses. This opens the way for further BEMM
investigations of current-induced magnetization dynamics.
