Evidence of Superconductivity Induced by Copper Doping in NbTe2 Single Crystals

NbTe 2 is a distorted monoclinic quasi-two-dimensional layered semimetal with superconductivity at 0.5 K. We report the investigation of the influence of Cu substitution on the superconductivity in NbTe 2 . Surprisingly, we found that a very small amount of Cu doing in Nb sites can greatly enhance the superconductivity of Nb 1− x Cu x Te 2 single crystal samples. The superconducting transition temperature increases 6 times to 3 K for the optimal composition Nb 0.95 Cu 0.05 Te 2 , and then decreases for higher x ; the superconducting transition temperature disappears when x = 0.1, which forms a dome-shaped superconducting phase diagram.