Self-Assembling Nanowires

Since the discovery of giant magnetoresistance, for which Albert Fert and Peter Grünberg have been awarded the 2007 Nobel Prize, thin magnetic films have attracted much interest. More particularly, multi-layered nanowires consisting of magnetic and nonmagnetic layers (FeNi/Cu, Ni/Cu, Fe/Cr, Co/Cu…) have been proven to exhibit outstanding properties which have straightforward applications: M-RAM (magnetic random access memories), nano-sensors, data storage… Most of the time, the bottle neck for the usage of such nanostructures is that their synthesis is not reliable, especially when it comes to producing very small wires, in the range of a few tens of nanometers diameter. We are exploring alternative synthesis routes in order to find a new self-ordering way of producing multilayered or core-shell nanowires which would be only based on diffusion processes and phase separation. Simply put, we would like to create a plain alloyed nanowire and provoke the formation of layers just by a well-designed heat treatment.
Fig. 2: Nickel nanowires coated with a copper layer, depending on the coating technique, the wires form different shapes (packages, nano-cactuses…)