Dresden 2020 – scientific programme
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MA: Fachverband Magnetismus
MA 50: Permanent Magnets
MA 50.7: Talk
Thursday, March 19, 2020, 16:45–17:00, HSZ 101
Interplay between chemical order and magnetic properties in L10 FeNi (tetrataenite): A First-Principles Study — •Ankit Izardar and Claude Ederer — Materials Theory, ETH Zuerich, Switzerland
The volatility in price and uncertainty of supply of rare earth elements has sparked great interest to explore permanent magnets that are free from rare-earth elements. One interesting candidate in this quest is a chemically-ordered L10 Fe50Ni50 found in iron meteorites. However, laboratory synthesis of the ordered phase is extremely challenging because of the slow diffusion of atoms at the rather low order-disorder transition temperature. Until now, only partially ordered samples have been synthesized. Therefore, it is important to know how deviations from perfect chemical order affect the magnetic properties.Using first-principles-based density-functional theory calculations in combination with Monte Carlo (MC) simulations, we investigate the interplay between chemical order and the magnetic properties of the L10 FeNi phase. We use a supercell approach to model structures with varying degree of chemical order in combination with the disordered local moment method to describe the paramagnetic state. Our calculations demonstrate a strong effect of the magnetic order on the chemical order-disorder transition temperature and vice-versa. Furthermore, we also investigate dependence of the magneto-crystalline anisotropy (MAE) on the chemical long range order. Our results indicate that small deviations from perfect order do not significantly decrease the MAE with respect to a completely ordered FeNi alloy.