Magnetic phase transition driven by nitrogen doping in Fe3Ga thin films

Magnetic phase transition holds considerable scientific and technological value in the field of spintronics, as it plays a crucial role in the manipulation and control of spin degrees of freedom. In this study, by controlling nitrogen doping, we demonstrate a magnetic phase transition in Fe3Ga thin films, shifting from a ferromagnetic insulator Fe3Ga with cubic structure to a ferromagnetic metal Fe3GaN with anti-perovskite structure. This transformation is likely associated with the lattice expansion induced by nitrogen incorporation and the resulting changes in the electronic structure of Fe atoms, as confirmed by x-ray diffraction, scanning transmission electron microscopy, and x-ray absorption spectroscopy analysis. With increasing nitrogen content, the valence state of Fe gradually increases, and the formation of Fe-N bonds alters the electronic state structure of Fe ions, leading to changes in both the conductivity and magnetic properties of Fe3GaN film. These findings indicate that adjusting the level of nitridation during growth can effectively tune the magnetic and electric properties of Fe3Ga epitaxial films, providing approaches for their application in spintronics.