EPITAXIAL GROWTH OF IRON NITRIDES BY MBE IN THE PRESENCE OF AN ATOMIC NITROGEN SOURCE

摘要

Despite the high mismatch of 10 % between the MgO substrate and the iron nitride phase, single-crystalline layers of γ'-Fe_4N were obtained. From precise X-ray measurements, a tetragonal distortion was found and also a tilt of about 1.2°between the nitride and the substrate planes. Possibly a periodicity in the misfit dislocation network is the cause of the observed strain. The unexpected tilt in one direction may be due to the asymmetry in the geometry during growth. Extensive Mossbauer experiments allowed determination of the easy axis of the magnetization along the <100> crystallographic direction of the γ'-Fe_4N phase. The smaller hyperfine fields obtained in the Mossbauer experiments may be correlated with the strain present in the nitride layer.