Coexisting structural phases in the catalytically driven growth of rock salt GdN

Abstract

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 N2 pressure. X-ray diffraction measurements show a strong (111) preferential orientation for all N2 pressure and the signature of a secondary phase of GdN that develops as the N2 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.