Computational screening of Fe-Ta hard magnetic phases

In this paper, we perform a systematic calculation of the Fe-Ta phase diagram to discover hard magnetic phases. By using structure prediction methods based on evolutionary algorithms, we identify two energetically stable magnetic structures: a tetragonal ${\mathrm{Fe}}₃\mathrm{Ta}$ (space group 122) and a cubic ${\mathrm{Fe}}₅\mathrm{Ta}$ (space group 216) binary phase. The tetragonal structure is estimated to have both high saturation magnetization (${\ensuremath{\mu}}₀{\mathrm{M}}_s=1.14$ T) and magnetocrystalline anisotropy (${\mathrm{K}}₁=2.17 \mathrm{MJ}/{\mathrm{m}}³$) suitable for permanent magnet applications. The high-throughput screening of magnetocrystalline anisotropy also reveals two low-energy metastable hard magnetic phases: ${\mathrm{Fe}}₅{\mathrm{Ta}}₂$ (space group 156) and ${\mathrm{Fe}}₆\mathrm{Ta}$ (space group 194), that may exhibit intrinsic magnetic properties comparable to ${\mathrm{SmCo}}₅$ and ${\mathrm{Nd}}₂{\mathrm{Fe}}₁₄\mathrm{B}$, respectively.