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

TL;DR

This study investigates how Pd substitution in AuTe2 induces structural changes and superconductivity, revealing a strong-coupling superconducting phase near a structural instability caused by the suppression of Te-Te dimers.

Contribution

It demonstrates the emergence of strong-coupling superconductivity linked to a composition-induced structural phase transition in Au$_{1-x}$Pd$_x$Te$_2$, highlighting the interplay between structural instability and superconductivity.

Findings

Superconductivity with $T_c$ up to 4.65 K appears near the structural phase transition.

Structural transition from monoclinic to trigonal is suppressed to zero temperature at $x$=0.55.

Strong coupling superconductivity is observed near the composition of structural instability.

Abstract

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 $T_{\rm c}$ = 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.