Manipulating the switching in modulated iron nanowires grown by focused electron beam induced deposition

Abstract

The future technological impact of smaller, faster and more efficient spintronic devices compared to current technologies inspires the quest of new approaches and strategies. Emerging non-conventional nanofabrication tools are required for this purpose. One attractive technique is focused electron beam induced deposition, a direct-writing process of ferromagnetic nano-objects. Here, we report the fabrication of highly pure iron wires with one-dimensional thickness modulation using diiron nonacarbonyl, Fe2(CO)9 as a starting material. For that purpose, we employ a strategy for the electron beam scanning method, in which the beam spots are separated a certain distance from each other in one direction during the deposition process. Magnetic properties of the wires have been experimentally studied by magneto-optical-Kerr microscopy and supported by micromagnetic simulations. Our results suggest that the thickness modulation induces a local magnetic anisotropy along the short axis on the iron wire, which is not present in wires with a uniform thickness. By the proposed writing strategy, the switching field in such modulated wires could be controlled due to changes in magnetostatic interactions. Based on our outcomes, we conjecture that this procedure can be valuable in research on the impact of one-dimensional thickness modulation in nano-objects and future spintronic devices.