Investigations to improve the thermal stability and magnetization of epitaxial Fe16N2 thin films by alloying with Al and Mn

Fe16N2 is known for having a giant saturation magnetization Ms (far above Fe-Co alloy), yet establishing it for high-performance permanent magnet applications is difficult due to its poor thermal stability and low magnetic anisotropy (MA). Fe16N2 can be a viable low-cost and environment friendly alternative due to its formation from the most plentiful elements, provided its thermal stability and MA can be improved while maintaining the high Ms. According to recent theoretical calculations, alloying Fe16N2 by varying the amount of valance electrons can be a successful strategy for simultaneously enhancing the MA and the thermal stability. Al and Mn were reported to be the most efficient dopants among a large range of metals. They are predicted to reduce the formation energy, increase the MA significantly, and preserve high Ms of Fe16N2. In the proposed study, reactive magnetron co-sputtering will be used to deposit epitaxial isotope multilayers of undoped, 5 at.% Al, and 5 at.% Mn doped [Fe15MN2 (5 nm)/57Fe15MN2 (5 nm)]x10 (M = Fe, Al, Mn) samples on MgO (001) substrate. The thermal stability by studying Fe self-diffusion and the Ms will then be assessed concurrently in pristine and vacuum annealed samples employing polarized neutron reflectivity. The obtained data will be utilized to establish the relationship between the dopant, thermal stability, and Ms of Fe16N2 in order to fulfill its potential as a high-performance permanent magnet.