  Here we report the effect of structural and superconductivity properties on
Ru doped CuIr2Te4 telluride chalcogenide. XRD results suggest that the
CuIr2-xRuxTe4 maintain the disordered trigonal structure with space group P3m1
(No. 164) for x less than 0.3. The lattice constants, a and c, both decrease
with increasing Ru content. Temperature-dependent resistivity, magnetic
susceptibility and specific-heat measurements are performed to characterize the
superconducting properties systematically. Our results suggest that the optimal
doping level for superconductivity in CuIr2-xRuxTe4 is x = 0.05, where Tc is
2.79 K with the Sommerfeld constant gamma of 11.52 mJ mol-1 K-2 and the
specific-heat anomaly at the superconducting transition, is approximately 1.51,
which is higher than the BCS value of 1.43, indicating CuIr1.95Ru0.05Te4 is a
strongly electron-phonon coupled superconductor. The values of lower critical
filed and upper critical field calculated from isothermal magnetization and
magneto-transport measurements are 0.98 KOe and 2.47 KOe respectively,
signifying that the compound is clearly a type-II superconductor. Finally, a
dome-like shape superconducting Tcs vs. x content phase diagram is established,
where the charge density wave disappears at x = 0.03 while superconducting
transition temperature (Tc) rises until it reaches its peak at x = 0.05, then,
with decreasing when x reaches 0.3. This feature of the competition between CDW
and the superconductivity could be caused by tuning the Fermi surface and
density of states with Ru chemical doping.

Superconductivity