We report the discovery of bulk superconductivity in Sc₆MTe₂ with seven kinds of transition-metal elements M. The critical temperatures for M = 3d elements are higher than those for 4d and 5d elements and increase in the order of M = Ni, Co, and Fe with the highest T_c of 4.7 K in Sc₆FeTe₂. First principles calculations indicate the presence of significant contribution of Fe 3d orbitals at the Fermi energy, which most likely enhance the T_c of Sc₆FeTe₂. The upper critical field for M = Os is considerably enhanced by the strong spin–orbit coupling. These results show Sc₆MTe₂ to constitute a unique family of d-electron superconductors, in which d electrons of 3d and 5d M atoms strongly influence the superconducting properties.

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