Superconducting Order from Disorder in 2H-TaSe$_{2-x}$S$_{x}$ (0$\leq$x$\leq$2)

TL;DR

This study demonstrates that alloying 2H-TaSe$_{2}$ with sulfur induces robust superconductivity, with critical temperatures exceeding those of the pure compounds, likely due to disorder suppressing charge density wave order.

Contribution

It reveals that disorder from alloying enhances superconductivity in 2H-TaSe$_{2-x}$S$_{x}$ by suppressing competing charge density wave order, a novel insight into tuning superconductivity.

Findings

Superconducting critical temperature peaks within the alloy series.

Disorder correlates with increased conductivity and higher T$_{c}$.

Suppression of charge density wave order favors superconductivity.

Abstract

We report on the emergence of robust superconducting order in single crystal alloys of 2H-TaSe$_{2-x}$S$_{x}$ (0$\leq$x$\leq$2) . The critical temperature of the alloy is surprisingly higher than that of the two end compounds TaSe$_{2}$ and TaS$_{2}$. The evolution of superconducting critical temperature T$_{c} (x)$ correlates with the full width at half maximum of the Bragg peaks and with the linear term of the high temperature resistivity. The conductivity of the crystals near the middle of the alloy series is higher or similar than that of either one of the end members 2H-TaSe$_{2}$ and/or 2H-TaS$_{2}$. It is known that in these materials superconductivity (SC) is in close competition with charge density wave (CDW) order. We interpret our experimental findings in a picture where disorder tilts this balance in favor of superconductivity by destroying the CDW order.