Magnetic properties of Fe (Ta/W) N ternary alloy: first principles and atomistic simulations.

Using the first principles method, we explored the magnetic properties of Fe (Ta/W) N alloy. We calculated the alloy formation energy, dynamical and thermal stabilities and proved the possibility of materialization of Fe (Ta/W) N alloy. The FeTaN had a Curie temperature of 1020 K while it was 950 K in FeWN. We found greatly enhanced uniaxial anisotropy in ternary alloy systems. Particularly, the FeWN alloy has a uniaxial anisotropy constant of 2.68 MJ m which is almost a five times enhancement of the value of 0.57 MJ m in the FeN. The increase in the uniaxial anisotropy resulted in an enhancement of the coercive field (H ). The FeWN had a coercive field of 27 kOe at 300 K and this is comparable to that of 25.6 kOe in Dy-doped Nd based magnet. Besides, the (BH) of 54.5 MGOe in FeWN alloy was even larger than the value of 40 MGOe in Dy-doped Nd-based magnet. Overall, we propose that the Fe (Ta/W) N can be a potential rare-earth-free permanent magnet.