Superconductivity in CuIr_2-xAl_xTe₄ telluride chalcogenides

The relationship between charge-density-wave (CDW) and superconductivity (SC), two vital physical phases in condensed matter physics, has always been the focus of scientists' research over the past decades. Motivated by this research hotspot, we systematically studied the physical properties of the layered telluride chalcogenide superconductors CuIr_2-xAl_xTe_4 (0 \leqslant x \leqslant 0.2). Through the resistance and magnetization measurements, we found that the CDW order was destroyed by a small amount of Al doping. Meanwhile, the superconducting transition temperature (T_\rm c) kept changing with the change of doping amount and rose towards the maximum value of 2.75 K when x=0.075. The value of normalized specific heat jump (\Delta C/\gamma T_\rm c) for the highest T_\rm c sample CuIr_1.925Al_0.075Te_4 was 1.53, which was larger than the BCS value of 1.43 and showed the bulk superconducting nature. In order to clearly show the relationship between SC and CDW states, we propose a phase diagram of T_\rm c vs. doping content.