Effect of Te doping on superconductivity and charge-density wave in dichalcogenides 2H-NbSe_2-xTe_x (x=0, 0.1, 0.2)

Single crystals of Te-doped dichalcogenides 2H-NbSe_2-xTe_x(x = 0, 0.10, 0.20) were grown by vapour transport method. The effect of Te doping on the superconducting and charge-density wave (CDW) transitions has been investigated. The sharp decrease of residual resistance ratio, RRR = R(300K)/R(8K), with increasing Te content was observed, indicating that the disorder in the conducting plane is induced by Te doping. Meanwhile the superconducting transition temperature, T_c, decreases monotonically with Te content. However, the CDW transition temperature, T_CDW, shown by a small jump in the temperature dependence of the resistivity near 30 K, increases slightly. The results show that the suppression of superconductivity might be caused by the enhancement of CDW ordering. The disorder has little influence on the CDW ordering.