In the quest for sustainable energy solutions, the demand for rare-earth-free permanent magnets has never been more pressing. A recent study published in the journal “Applied Surface Science Advances” (which translates to “Advances in Surface Science Applications”) sheds light on a promising avenue for developing these magnets, focusing on the role of copper (Cu) doping in enhancing the magnetic properties of equiatomic FeNi films. The research, led by Ashish Gupta from the UGC-DAE Consortium for Scientific Research in Indore, India, explores how Cu doping can accelerate the formation of the highly desirable L10-ordered FeNi phase, known as tetrataenite, which boasts high magnetocrystalline anisotropy and saturation magnetization.
The challenge with tetrataenite has always been its slow diffusion kinetics, which hinder atomic ordering under normal conditions. Gupta and his team investigated chemically homogeneous multilayers of equiatomic FeNi and Cu-doped FeNi (5 at.%) to understand the correlation between self-diffusion and magnetism. Their findings reveal that Cu doping substantially increases self-diffusion, facilitating the grain boundary diffusion necessary for atomic ordering.
“Cu is known for accelerating atomic interdiffusion and promoting chemical disorder,” Gupta explains. “This can significantly enhance the formation of ordered phases in FeNi systems, which is crucial for developing rare-earth-free permanent magnets.”
The team employed nuclear resonance reflectivity and forward scattering measurements on both as-deposited and annealed samples. Their results showed that Cu doping leads to significant changes in the local magnetic environment, as confirmed by conversion electron Mössbauer spectroscopy. Although the net magnetic moment remained nearly unchanged, the Cu-doped sample exhibited an enhancement in coercivity at 573 K, as quantified by SQUID-VSM.
These observations highlight the potential of Cu-assisted diffusion channels to facilitate the formation of ordered phases in FeNi systems. The implications for the energy sector are profound, as the development of rare-earth-free permanent magnets could reduce dependence on scarce and expensive rare-earth elements, making sustainable energy technologies more accessible and affordable.
As Gupta notes, “This research opens up new possibilities for the strategic development of rare-earth-free permanent magnets, which are essential for various applications in the energy sector, including wind turbines and electric vehicles.”
The study not only advances our understanding of the role of Cu doping in promoting diffusion-assisted evolution of magnetic properties but also paves the way for future developments in the field of sustainable energy technologies. By leveraging the unique properties of Cu-doped FeNi films, researchers can potentially overcome the challenges associated with the slow diffusion kinetics of tetrataenite, bringing us one step closer to a more sustainable energy future.