High-temperature soft magnetic properties of antiperovskite nitrides ZnNFe3 and AlNFe3

• A two-step synthetic method for high quality ZnNFe3 and AlNFe3 was demonstrated.
• High Curie temperature and saturated magnetization but low coercive fields are observed.
• The specific heat and electrical/thermal transport properties are investigated.

We report the synthesis, crystal structure, magnetic and electrical/thermal transport properties of antiperovskite nitrides ZnNFe3 and AlNFe3. Both compounds display ferromagnetic (FM) ground state and transform into the paramagnetic phase at 762 K and 770 K, respectively. At FM phase, for ZnNFe3 and AlNFe3, the saturated magnetizations at 5 K are 163 and 188 emu/g, which is the largest value among all the antiperovskite compounds; the minimal coercive forces (HC) are as low as 18.6 and 16.3 Oe; the low HC is almost constant covering a broad temperature range of 5–650 K. These characteristics indicate that both ZnNFe3 and AlNFe3 may be promising candidates of high-temperature soft magnetic material. In addition, electrons are dominant carriers owing to the negative Seebeck coefficient, the Fermi-liquid behavior is well presented via the investigation of low-temperature electrical transport, and the lattice thermal conductivity estimated by Wiedemann–Franz law is the main part of total thermal conductivity at high temperatures for both ZnNFe3 and AlNFe3.