Ion damage during preparation of nanostructures in magnetite by means of focused ion-beam (FIB) milling

Nanostructures are prepared into magnetite (Fe3O4) thin films on (0 0 1) MgO substrates by means of focused ion-beam (FIB) milling. The resulting ion damage is analyzed using electron backscatter diffraction (EBSD), enabling the determination of crystal orientation with a spatial resolution of about 40 nm. Depending on the ion currents and radiation dose applied during the FIB milling, different types of damage are observed. At high ion currents, an entire ring area around the nanostructure is affected by the ion beam. The EBSD analysis reveals that new, small grains with a different orientation pattern are created within the ring area. At small ion currents, proper nanostructures can be created with only minimal damage to the remainder of the film.