Composition-induced structural instability and strong-coupling superconductivity in Au1-xPdxTe2

The physical properties and structural evolution of the MX2-type solid solution Au1-xPdxTe2 are reported. The end member AuTe2 is a normal metal with a monoclinic distorted CdI2-type structure with preformed Te-Te dimers. A monoclinic-trigonal structural phase transition at a finite temperature occurs upon Pd substitution and is suppressed to zero temperature near x = 0.55, and a superconducting phase with a maximum T-c = 4.65 K emerges. A clear indication of strong-coupling superconductivity is observed near the composition of the structural instability. The competitive relationship between Te-Te dimers and superconductivity is proposed.