Co doping effects on superconductivity of FeSe0.4Te0.6 single crystals

The Co substitution effects on the superconductivity of FeSe0.4Te0.6 single crystals were investigated. The magnetic susceptibility measurement suggests that Co is non-magnetic in these materials. The superconducting transition temperature decreases linearly for Co doping with the rate -0.75 K/Co%, while the increasing rate of residual resistivity is less than 12.5 μΩácm/Co%. Our data do not contradict the expectation for the s± pairing.