Epitaxial growth and magnetic properties of Ni<i>x</i>Fe4-<i>x</i>N (<i>x</i> = 0, 1, 3, and 4) films on SrTiO3(001) substrates

Abstract

The 20–60 nm-thick epitaxial NixFe4-xN (x = 0, 1, 3, and 4) films were successfully fabricated on SrTiO3(001) single-crystal substrates by alternating the substrate temperature (Tsub), and their crystalline qualities and magnetic properties were investigated. It was found that the crystal orientation and the degree of order of N site were improved with the increase of Tsub for x = 1 and 3. The lattice constant and saturation magnetization decreased as the Ni content increased. This tendency was in good agreement with first-principle calculation. Curie temperature of the Ni3FeN film was estimated to be 266 K from the temperature dependence of magnetization. The Ni4N film was not ferromagnetic but paramagnetic due to its low degree of order of N site.