Nanopatterning of a thin ferromagnetic CoFe film by focused-ion-beam irradiation

High-resolution magnetic patterning of a thin CoFe layer has been performed by irradiation using a focused-ion-beam system. Features <50 nm wide were formed reproducibly. The irradiated pattern comprised sets of alternating 3.0- and 1.0-μm-long magnetic wires, 100 nm wide. During magnetization reversal, the longer wires reversed at a lower field resulting in the formation of an ordered array of domains with density 10 μm-1 supporting antiparallel magnetization. The ability to create domains at predefined locations is important both for fundamental studies and technological applications