A route to break molecular nitrogen (N 2 ) under mild conditions is demonstrated by N 2 gas cracking on, and incorporation into, lanthanide films. Successful growth of lanthanide nitride thin films, made by evaporation of lanthanides in a partial N 2 atmosphere at room temperature and pressure as low as 10 –4 Torr, is confirmed using X-ray diffraction. In situ conductance measurements of pure lanthanide thin films exposed to N 2 gas show an immediate surface reaction and a slower bulk reaction. Finally, we report partial reversal of the nitrogen incorporation in a lanthanide nitride by cycling vacuum and nitrogen conditions in the sample chamber.

We present a study of polycrystalline thin films of the rock salt rare earth nitride GdN grown on amorphous fused silica at ambient temperature with varying N 2 pressure. X-ray diffraction measurements show a strong (111) preferential orientation for all N 2 pressure and the signature of a secondary phase of GdN that develops as the N 2 pressure decreases. The secondary phase is found to have a smaller lattice parameter than the near-stoichiometric GdN. Raman spectroscopy, electrical and magnetic results support the coexistence of such mixed-phase samples with the lattice distortion originating from nitrogen vacancies. Significantly the magnetic data show an increase of the ferromagnetic onset temperature as the secondary phase develops, without affecting the soft ferromagnetic character of GdN.

We report on the effect of the nitrogen to rare earth (N2/RE) flux ratio on the structural, transport, and magnetic properties of samarium nitride (SmN) and dysprosium nitride (DyN) thin films. Both materials display a reduced lattice constant when the N2/RE flux ratio decreases, i.e., with increased nitrogen vacancies (VN) concentration. The films show several orders of magnitude increase in the electrical resistivity with increased N2/RE flux ratio. Finally, magnetic measurements on DyN films display a deviation from the free ion moment at low temperature, which is eased in more conductive films. This was interpreted as a further reduction in the quenching of the orbital angular momentum caused by the increased VN concentration. The Curie temperature was also found to increase with VN.