Composition-induced structural instability and strong-coupling superconductivity in Au_(1-x)Pd_xTe_2

摘要

The physical properties and structural evolution of the M X_2-type solid solution Au_(1-x)Pd_xTe_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_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.