Nitrided FeNi: Chemical versus magnetovolume effects from ab initio

Abstract Magnetic, magneto-volume properties and bonding analyses of binary intermetallic FeNi and its nitride FeNiN have been investigated within density functional theory DFT. From total energy calculations and establishing the energy-volume equations of states (EOS) the ground state of both compounds is ferromagnetic with a reduced magnetization of the nitrided intermetallic due to spin pairing between Fe/Ni and N. The volume expansion indicates that iron shows itinerant magnetism, whereas Ni exhibits a localized behavior. Important magneto-volume effects are observed whereby saturation of the magnetic moment is reached in FeNi but not in FeNiN. The chemical bonding shows Ni-N and Fe-N contributions to the stability of the nitride systems. However, this bonding, which reduces magnetization around experimental volume, loses its effect at large volumes where magneto-volume influence prevails again as in FeNi.