Characterization of a new cobalt precursor for focused beam deposition of magnetic nanostructures

The electrical and magnetic properties of nanowires deposited from cobalt tricarbonyl nitrosyl (Co(CO)3NO) precursor by focused electron beam- and focused ion beam-induced deposition (FEBID and FIBID) have been investigated. As-deposited nanowires have similar Co content, around 50–55at.%, but different electrical behaviour: FEBID nanowire is highly resistive (6.3mΩcm at RT) and non-metallic at low T, while the FIBID one has much lower resistivity (189μΩcm at RT) and it is metallic. The magnetic properties, tested with magnetoresistance measurements, reveal a non-magnetic behaviour for both nanowires. After 400°C annealing in vacuum FEBID wire is much less resistive (62μΩcm at RT) and recovers the metallic behaviour at low T, and both FEBID and FIBID wires display ferromagnetic behaviour. Structural analysis by low energy-scanning transmission electron microscopy (LE-STEM) suggests that coarsening and interconnection of the Co nanograins are responsible for the improvement in electrical and magnetic properties.