Structure and properties of ternary manganese nitride Mn ₃CuN_y thin films fabricated by facing target magnetron sputtering

Deposition of Mn₃CuN_y thin films on single crystal Si (1 0 0) at various substrate temperatures (T_sub) by facing target magnetron sputtering is reported. The crystal structure and composition were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results confirmed that the crystalline antiperovskite Mn ₃CuN_y thin film with (2 0 0) highly preferred texture had been obtained at T_sub = 180 °C. Furthermore, for the resulting Mn₃CuN_y thin film, it showed different properties compared with the bulk counterpart. There was a paramagnetic to ferrimagnetic transition at 225 K with decreasing temperature. The change of the lattice constant with temperature presented positive thermal expansion behavior and no structural transition was observed. The average linear thermal expansion coefficient (α) is 2.49 × 10^-5 K^-1 from 123 K to 298 K. More interestingly, the temperature dependence of resistivity displayed a semiconductor-like behavior, i.e. an obvious monotonous decrease of resistivity with increasing temperature.