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

Samir F. Matar (1) , Abdesalem Houari (2) , Mohamed-Akli Belkhir (2) , Mirvat Zakhour (3)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
2 Laboratoire de Physique Théorique, Departement de Physique
3 LCPM - Laboratoire de Chimie Physique des Matériaux

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.

Mots clés: Ternary iron nitrides; Magnetic properties; Magnetovolume effects; Invar-like behavior; Covalent magnetism

Domaines: Matériaux; Chimie inorganique; Chimie théorique et/ou physique

Samir F. Matar, Abdesalem Houari, Mohamed-Akli Belkhir, Mirvat Zakhour. "Covalent magnetism" and invar-like behavior within ternary nitrides : an ab initio study. Zeitschrift fur Naturforschung B, 2007, 62 (7), pp.881-890. ⟨10.1515/znb-2007-0702⟩. ⟨hal-00158018⟩