Effect of the nitrogen-argon gas mixtures on the superconductivity properties of reactively sputtered molybdenum nitride thin films

We report on the superconducting properties of molybdenum nitride thin films grown by reactive DC sputtering at room temperature with a N2:Ar mixture. Thin films grown using 5 % N2 concentration display Tc = 8 K, which is gradually reduced and abruptly disappears for 40 % N2 concentration. This suppression can be associated with changes in the nitrogen stoichiometry from Mo2N to MoN. Our results provide an effective and simple path to prepare Mo2Nx thin films with tunable Tc, which is relevant for the investigation of the fundamental properties and for technological applications.