The Fe-N system presents a variety of phases, with the crystal structure and the magnetic properties evolving with nitrogen concentrations. In particular, some of these phases do not show ferromagnetism at room temperature (e.g., the Curie temperature is between 4 and 60 K for Fe2N phase). Thus, one can expect an interesting temperature dependence of Fe/Fe-N system with a limited N content.

Fe/Fe-N multilayers have been grown at the Institute of Physics of the Polish Academy of Sciences in Warsaw. Several Fe(4 nm)/Fe-N(0.8-1.5 nm) samples were deposited on (001)-oriented GaAs substrates at room temperature by a sputtering technique. Neutron diffraction measurements and spin-polarized neutron reflectometry demonstrated a presence of magnetic stripe domains in investigated multialyers, with a period varying with the Fe-N layer thickness, typically between 180 and 240 nm. The magnetic stripe domain structure on the surface of these samples was also directly demonstrated by the magnetic force microscope (MFM).

The goal of the present paper was to analyze the domain structure above mentioned as a function of an external magnetic field and the sample orientation. The neutron scattering data were completed by the results of Kerr magnetometry, performed at room temperature.