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MA: Fachverband Magnetismus

MA 50: Permanent Magnets

MA 50.3: Vortrag

Donnerstag, 19. März 2020, 15:30–15:45, HSZ 101

Computational screening of Fe-Ta magnetic phases — •Sergiu Arapan¹, Pablo Nieves¹, Heike C. Herper², and Dominik Legut¹ — ¹IT4Innovations, VŠB - Technical University of Ostrava, 17. listopadu 15, 70833 Ostrava-Poruba, Czech Republic — ²Department of Physics and Astronomy, Uppsala University, Box 516, 75121 Uppsala, Sweden

In this work we perform a systematic calculation of the Fe-Ta phase diagram. Despite of the fact that the two experimentally observed ordered Fe-Ta alloy phases do not exhibit magnetic properties suitable for permanent magnets (PMs), our computational study suggests that new phases, with intrinsic magnetic properties appropriate for PMs, might exist within this binary system. By using structure prediction methods based on evolutionary algorithms and density functional theory, we identify two energetically stable magnetic structures: a tetragonal Fe₃Ta (space group 122) and a cubic Fe₅Ta (space group 216) binary phases. The tetragonal structure is estimated to have both high saturation magnetization (µ₀M_s=1.14 T) and magneto-crystalline anisotropy (K₁=2.17 MJ/m³) suitable for permanent magnet applications. In addition, we discover two metastable hard magnetic phases: Fe₅Ta₂ (space group 156) and Fe₆Ta (space group 194), that may exhibit intrinsic magnetic properties comparable to SmCo₅ and Nd₂Fe₁₄B, respectively. From the results of electronic structure calculations we determine electronic states responsible for such large MAE and identify a criterion to find hard magnetic structures in rare-earth free intermetallic systems.