Superconductivity in Ternary Zirconium Telluride Zr6MTe2 with 3d Transition Metals

We report the synthesis, electronic properties, and electronic states of Zr6MTe2 (M = Cr, Mn, Fe, and Co), which is isostructural to a recently discovered superconductor family Sc6MTe2. Based on the electrical resistivity and heat capacity data measured at low temperatures, Zr6FeTe2 is found to show bulk superconductivity below Tc = 0.76 K. Zr6CoTe2 also exhibited zero resistivity due to superconductivity below 0.13 K. In contrast, Zr6+delta Mn1-delta Te2 does not show superconductivity but instead exhibits strong magnetism, which most likely prevents the formation of super-conductivity in this material. The electronic properties and electronic states of Zr6MTe2 are discussed in comparison with those of Sc6MTe2.