Mechanisms of epitaxial growth and magnetic properties ofγ′−Fe4N(100)films onCu(100)

Abstract

Thin films of iron nitride have been grown on $\mathrm{Cu}(100)$ single-crystals by molecular beam epitaxy of $\mathrm{Fe}$ in the presence of a beam of atomic $\mathrm{N}$ provided by a radio-frequency plasma source. Under the appropriate growth conditions, the films are high-quality, epitaxial, single-phase ${\ensuremath{\gamma}}^{\ensuremath{'}}\text{\ensuremath{-}}{\mathrm{Fe}}_{4}\mathrm{N}\phantom{\rule{0.3em}{0ex}}(100)$. The mechanisms of growth have been studied from the early stages by scanning tunneling microscopy, low energy electron diffraction and Auger electron spectroscopy, that show that the interface with the $\mathrm{Cu}$ substrate is very sharp, the intermixing between the growing film and the $\mathrm{Cu}$ substrate being limited to few monolayers. The film grows layer by layer. M\ossbauer spectroscopy and Kerr effect measurements confirm that the films are magnetic at room temperature, with the easy axis in the plane of the film and parallel to the $⟨100⟩$ direction.