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

Satoshi Kokado·Nobuhisa Fujima·Kikuo Harigaya·Hisashi Shimizu·Akimasa Sakuma
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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 $P = (σ_\uparrow - σ_\downarrow) / (σ_\uparrow + σ_\downarrow )$, with $σ_{\uparrow(\downarrow)}$ 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 $|P|$.

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Satoshi Kokado, Nobuhisa Fujima, Kikuo Harigaya, Hisashi Shimizu, Akimasa Sakuma. 2006-04-28. A theoretical analysis on highly spin-polarized transport of iron nitride Fe_4N. https://doi.org/10.1103/physrevb.73.172410

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