Doping effects of Sb in FeTe1−xSbx single crystals

We investigated the doping effects of Sb on the magnetic, transport and structural properties in FeTe1−xSbx single crystals. Resistivity, magnetic susceptibility and heat capacity experiments consistently reveal that the magnetic/structural transition temperature TN∼70K in undoped Fe1.05Te is gradually suppressed by Sb doping, but no superconductivity is observed for x up to 10%. It is found that the electronic heat capacity coefficient γ increases with Sb content, implying the increase of the density of states at Fermi level. Referring to previous calculation reports, this means that the Sb substituent plays a role of hole carrier doping, which is consistent with our measurements on Hall coefficient. Structural analysis shows that Sb doping induces an expansion of the lattice along the a axis and a shrinkage along the c axis. Our work suggests that the antiferromagnetism in Fe1+yTe may be different in nature with other parent compounds of FeAs-based systems.