A theoretical analysis on highly spin-polarized transport of iron nitride Fe_4N

Abstract

In order to propose a ferromagnet exhibiting highly spin-polarized transport, we theoretically analyzed the spin polarization ratio of the conductivity of the bulk Fe${}_4$N with a perovskite type structure, in which N is located at the body center position of fcc-Fe. The spin polarization ratio is defined by $P=({\sigma }_{\uparrow }-{\sigma }_{\downarrow })/({\sigma }_{\uparrow }+{\sigma }_{\downarrow })$, with ${\sigma }_{\uparrow (\downarrow )}$ being the conductivity at zero temperature of the up spin (down spin). The conductivity is obtained by using the Kubo formula and the Slater-Koster tight binding model, where parameters are determined from the least-square fitting of the dispersion curves by the tight binding model to those by the first principles calculation. In the vicinity of the Fermi energy, $|P|$ takes almost 1.0, indicating perfectly spin-polarized transport. In addition, by comparing Fe${}_4$N to fcc-Fe (Fe${}_4$N${}_0$) in the ferromagnetic state with the equilibrium lattice constant of Fe${}_4$N, it is shown that the non-magnetic atom N plays an important role in increasing $|P|$.

4 pages, 2 figures, accepted for publication in Phys. Rev. B

References in corpus (1)

• Magnetoresistance Effect in Spin-Polarized Junctions of Ferromagnetically Contacting Multiple Conductive Paths: Applications to Atomic Wires and Carbon Nanotubes