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

The physical properties and structural evolution of the MX${}_2$-type solid solution Au${}_{1-x}$Pd${}_x$Te${}_2$ are reported. The end member AuTe${}_2$ is a normal metal with a monoclinic distorted CdI${}_2$-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 $T_{\mathrm{c}}$ = 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.