7 research outputs found
Prediction of Ferromagnetic Ground State of NaCl-type FeN
Ab-initio results for structural and electronic properties of NaCl-type FeN
are presented in a framework of plane-wave and ultrasoft pseudopotentials.
Competition among different magnetic ordering is examined. We find the
ferromagnetic phase stable overall. Stabilization over the unpolarized phase is
obtained by splitting one flat t_2g-type band crossing the Fermi energy. A
comparison with CrN is considered. We find large differences in the properties
of the two systems that can be addressed to the smaller ionicity and
magnetization of FeN.Comment: 5 pages, 4 figures, twocolumn latex style Sentence changed in Section
III line 1
Electronic structure and magnetism of equiatomic FeN
In order to investigate the phase stability of equiatomic FeN compounds and
the structure-dependent magnetic properties, the electronic structure and total
energy of FeN with NaCl, ZnS and CsCl structures and various magnetic
configurations are calculated using the first-principles TB-LMTO-ASA method.
Among all the FeN phases considered, the antiferromagnetic NaCl structure with
q=(00pi) is found to have the lowest energy at the theoretical equilibrium
volume. However, the FM NaCl phase lies only 1mRyd higher. The estimated
equilibrium lattice constant for nonmagnetic ZnS-type FeN agrees quite well
with the experimental value, but for the AFM NaCl phase the estimated value is
6.7% smaller than that observed experimentally. For ZnS-type FeN, metastable
magnetic states are found for volumes larger than the equilibrium value. On the
basis of an analysis of the atom- and orbital-projected density of states and
orbital-projected Crystal Orbital Hamilton Population, the iron-nitrogen
interactions in NM ZnS, AFM NaCl and FM CsCl structures are discussed. The
leading Fe-N interactions is due to the d-p iron-nitrogen hybridization, while
considerable s-p and p-p hybridizations are also observed in all three phases.
The iron magnetic moment in FeN is found to be highly sensitive to the
nearest-neighboring Fe-N distance. In particular, the magnetic moment shows an
abrupt drop from a value of about 2 muB to zero with the reduction of the Fe-N
distance for the ZnS and CsCl structures.Comment: 12 pages, 6 figure