We prepared CoxFe4- xN (x = 0, 1, 3) films on SrTiO3(STO)(001) substrates by molecular beam epitaxy. The epitaxial relationship with CoxFe4- xN(001) || STO(001) was confirmed by ω-2θ (out-of-plane) and ∅-2θχ(in-plane) x-ray diffraction (XRD) measurements. The degree of order of atoms (S) in the CoxFe4- xN films was estimated to be ∼0.5 by the peak intensity ratio of CoxFe4- xN(100) (superlattice diffraction line) to (400) (fundamental diffraction line) in the ∅-2θχXRD patterns. Conversion electron Mössbauer spectroscopy studies for the CoxFe4- xN films revealed that some N atoms are located at interstitial sites between the two nearest corner sites in the CoxFe4- xN films, and/or Fe atoms are located at both the corner and face-centered sites in the CoFe3N and Co3FeN films. In order to realize high spin-polarized CoxFe4- xN films having large S, further optimization of growth condition is required to prevent the site-disorders.
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