Electrochemistry for L1₀ alloys (FeNi, FePt, CoPt)

Alloys of iron (Fe) and nickel (Ni) which have a special arrangement of the atoms (the L1₀ structure) have excellent magnetic properties, which are competitive with those of the rare earth magnets.Thus L1₀ FeNi is promising for the development of a next-generation permanent magnet, with no content of critical raw elements. L1₀-FeNi has only been found in some meteorites until now. Cyclic electrochemical oxidation and reduction may be an original route toward the formation of L1₀-FeNi.

Together with European Partners, we work in the M-ERA.NET COSMAG project to work out how to produce it on earth, in a short time-scale. Our research at TU Chemnitz aims to increase the atomic mobility of Fe and Ni using non-equilibrium methods such as cyclic electrochemical oxidation and reduction to form L1₀-FeNi.

For this, we rely on our experience on the electrochemical deposition and manipulation of L1₀ FePt and CoPt films:

- Electric-field control of magnetism by reversible surface reduction and oxidation reactions, Phys. Rev. B. 87, 224411, 2013. doi.org/10.1103/PhysRevB.87.224411.

- Electrode processes and in situ magnetic measurements of FePt films in a LiPF6 based electrolyte. Electrochim. Acta 81, 330, 2012. doi.org/10.1016/j.electacta.2012.07.055.

- Electrodeposition and hard magnetic properties of Co–Pt films in comparison to Fe–Pt films, J. Magn. Magn. Mater. 314, 116, 2007. doi.org/10.1016/j.jmmm.2007.02.146

- Highly coercive electrodeposited FePt  films by postannealing in hydrogen, APL 85, 3498, 2004. doi.org/10.1063/1.1807958