Effects of Mo Doping on the Superconducting Properties of NbSe ₂

Transition metal dichalcogenides (TMDs) exhibit remarkable tunability in their structural and electronic properties, making them an excellent platform for exploring quantum phases in two-dimensional materials. Among these, 2H-NbSe2 is a classic TMD superconductor that shows conventional superconductivity with a relatively high superconducting transition temperature (Tc) of 7.2 K. In this study, we investigate the effect of Mo doping at the Nb site in NbSe2, creating the alloy system Nb1–xMoxSe2 (0 ≤ x ≤ 0.15). Notably, a slight increase in Tc is observed at a low doping level of x = 0.01, followed by a gradual decrease as Mo content increases, indicating a nonmonotonic relationship between superconductivity and Mo doping. We also found that the critical current density Jc increased by approximately 26% for x = 0.01 compared to undoped NbSe2. The upper critical field (Bc2) is estimated to be approximately 14.71 T for the x = 0.01 sample, which is among the highest reported values for polycrystalline NbSe2, indicating a significant enhancement in the robustness of the superconducting state of NbSe2 at low Mo doping levels.