Effect of Cu doping on structural and magnetic properties of antiperovskite Mn₃Ni(Cu)N thin films

Abstract Antiperovskite Mn₃Ni(Cu)N thin films with different Cu content were prepared on Si substrate by reactive magnetron sputtering. The effects of Cu addition on the crystal structure, surface morphology and magnetic property of Mn₃Ni(Cu)N thin films were investigated. As a result, the preferred orientation is independent to Cu-doping in the Mn₃Ni(Cu)N phase, while the addition of Cu induces the lattice expansion for the films, indicating the possibility of controlling the crystal orientation and the substitution of Cu for Ni. Correspondingly, the surface morphologies significantly vary with the Cu-doping. In particular, it is found that increase in Cu content changes the ground state from antiferromagnetic (AFM) to ferrimagnetic (FI) phase and the magnetic transition temperature gradually decreases within the testing temperature ranges, which is mainly attributed to the competition between FI and AFM interactions with increasing Cu-doping content. The present discovery highlights the potential application of magnetic materials.