Superconducting order from disorder in 2H-TaSe2−xSx

We report on the emergence of robust superconducting order in single crystal alloys of TaSe 2 − x S x (0 ≤ × ≤ 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 is in close competition with charge density wave order. We interpret our experimental findings in a picture where disorder tilts this balance in favor of superconductivity by destroying the charge density wave order. Condensed matter physics: crystallographic disorder enhances superconductivity Substituting sulfur into TaSe 2 induces disorder, which further helps to enhance superconductivity, with a higher transition temperature. It is higher than that of either TaSe 2 or TaS 2 . An international team of researchers led by Cedomir Petrovic at Brookhaven national laboratory of USA synthesized single crystal alloys of TaSe 2 − x S x and measured the electrical conductivity and superconducting transition temperature as a function of x . They found that the transition temperature optimally increased when a maximal disorder is introduced by substituting sulfur into TaSe 2 . The role of such a disorder was understood as to suppress other competing orders while keeping superconductivity intact. By breaking other orders, conducting carriers were released so that they contributed further to superconductivity. These results highlight a benefit role of disorder and provide a possible way to enhance superconductivity.