Covalent magnetism" and invar-like behavior within ternary nitrides : an ab initio study

Overview & Synopsis

Magnetic properties and bonding analyses of perovskite structure-derivedTFe3N(T=Ru,Os)nitrides have been investigated within density functional theory using both pseudo potential and allelectron methods. At equilibrium, spin degenerate non-magnetic (NM) and ferromagnetic (FM) cal-culations of energyversusvolume show that the ground state of the two compounds is ferromagnetic.Magnetic moments of Ru/Os and Fe, respectively, being situated at two different crystallographicsites are studied over a wide range of the cubic lattice parameter. The volume expansion indicatesthat iron atoms show itinerant magnetism while Ru and Os exhibit a localized behavior. Importantmagnetovolume effects are observed, with saturation of the magnetic moment reached in RuFe3Nbutnot in OsFe3N. The electronic structure is visualized for the different binding characters Fe–Nver-susRu/Os–N with the help of electron localization plots. The density of states of the ferromagneticground state is interpreted on the basis of a covalent magnetic model which goes beyond the Stonerrigid band model. An Invar-like behavior is predicted for the two nitrides.