Iron nitrides substituted with transition metals: DFT study of promising systems for anomalous Nernst effect

The anomalous Nernst effect is studied by ab initio calculations in substituted iron nitrides with antiperovskite structure Fe3M1N and Fe2M1M2N (M1 = 4d or 5d, and M2 = 3d transition metals), considering the intrinsic Berry curvature-related mechanism depending only on the band structure. The highest absolute anomalous Nernst conductivity (ANC) 8 A K-1 m-1 with a negative sign is calculated for ruthenium substituted ferromagnetic phase Fe3RuN. A similar maximum ANC is determined for ferrimagnetic phase Fe2RuCrN, yet the advantage of this doubly substituted phase is that the high ANC values persist over a wider temperature range. Comparable ANCs have so far only been determined for compounds with critical temperatures of magnetic ordering below room temperature, while substituted iron nitrides exhibit TC well above room temperature. Therefore, we propose Fe2RuCrN, composed from nontoxic, and except for Ru, also fairly abundant elements, as a starting stoichiometry for further experimental study of candidates for devices possessing a high ANC and suitable for room- and high-temperature applications.