Jumping the Gap: Can Tetrataenite Become a ‘Hard’ Permanent Magnet?
Date:
Contributed talk at the 27th International Workshop on Rare Earth and Future Permanent Magnets and their Applications (REPM 2023).
Abstract
Tetrataenite, a ferromagnetic, extraterrestrial mineral comprised of iron and nickel arranged in a unique atomically ordered fashion, is under scrutiny as a sustainable advanced permanent magnet for escalating renewable energy aspirations in the transition to a global low-carbon economy. Tetrataenite’s intermediate magnetocrystalline anisotropy (MCA) currently designates it as a “semi-hard” magnetic material. Its empirical hardness parameter is less than unity, categorizing it as a potential “gap magnet” with maximum stored energy between that of the weaker oxide magnetic materials and the rare-earth supermagnets, NdFeB, SmCo, etc. However, all experimental reports of tetrataenite’s MCA, measured from unoptimized natural materials or from highly out-of-equilibrium synthesized forms, are significantly greater than ab initio computational determinations which assume perfect atomic order within the lattice [1]. This result is striking since such computational outcomes show great fidelity when applied to other ferromagnetic transition-metal-based compounds with tetrataenite’s ordered crystal structure (FePt, FePd, CoPt) [2]. The computations also show a significantly diminished MCA for imperfectly ordered crystal structures [3]. In this work, new ab initio computational modeling reveals that undiscovered phenomena impacting Fe-Ni interatomic interactions must be in play. These results suggest that atomically optimized, highly ordered tetrataenite may indeed be included in the category of a truly “hard” ferromagnetic material with a hardness parameter greater than unity, accompanied by decisive technological relevance.
Acknowledgements
This work was supported in part by the U.S. Department of Energy under Award Number DE SC0022168, by the NSF under Award Number 2118164, and by the U.K. EPSRC Grant No. EP/W021331/1.
References
[1] M. Werwinski and W. Marciniak, J. Phys. D: Appl. Phys. 50 495008 (2017).
[2] J. B. Staunton et al., Phys. Rev. Lett. 93, 257204 (2004).
[3] J. B. Staunton et al., J. Phys.: Condens. Matter 16 S5623 (2004).