Superconductivity in CuIr _2–x Al _x Te₄ telluride chalcogenides

Abstract

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 CuIr2-x Al x Te4 (0 ≤ x ≤ 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 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 (ΔC/γT c ) for the highest T c sample CuIr1.925Al0.075Te4 was 1.53, which was larger than the BCS value of 1.43 and showed that bulk superconducting nature. In order to clearly show the relationship between SC and CDW states, we propose a phase diagram of T c vs. doping content.

Superconducting dome associated with the suppression and re-emergence of charge density wave states upon sulfur substitution in CuIr2Te4 chalcogenides

“…Concretely, the CDW signature in the resistivity disappears with a small S doping content x, whereas it reemerges for 0.2 x 0.5 and is enhanced as x increases in the doping range of 0.2 to 0.5. This phenomenon is similar to the case of single doped Cu 1−x Ag x Ir 2−y Zr y Te 4−z (I/Se) z [22,32,60,61], but it differs from the CuIr 2−x (Ru/Ti) x Te 4 and Cu 0.5−x Zn x IrTe 2 systems without reappearance of CDW transition in the high doping range [21,31,62]. Meanwhile, light blue represents the emergence and evolution of SC upon sulfur substitution, in which a small amount S substitution for Te can slightly enhance the T c and yields the highest T c of about 2.82 K at x = 0.15 for which the improvement of the SC may be due to the enhanced in electron-phonon coupling induced by the S doping, followed by a drop of T c where the degradation of T c is may due to the continuous shrinkage of the lattice which is not beneficial for the SC, which was observed in some other reported superconductors…”

“…From figure S7, it can see the dχ/dT transition is getting broader with the increasing of S doping content and the dχ/dT transition vanishes when x = 0.5. From resistivity and magnetic susceptibility results, we can see that only layered phases show SC with T c slightly ascending with x increasing and attains the highest value of 2.82 K for CuIr 2 Te 3.85 S 0.15 , which is rather higher than the T c obtained by the optimal Ru (2.79 K) and Al doping (2.75 K) [23,31]. Subsequently, there is a small drop of T c with the increase of x and a SC dome can be observed.…”

“…Finally, the lower critical field (μ 0 H c1 (0)) at zero temperature for the CuIr 2 Te 3.85 S 0.15 compound is calculated to be 17 mT. Compared to the pristine CuIr 2 Te 4 compound (28 mT) and Ru doping compound CuIr 1.95 Ru 0.05 Te 4 (98 mT) [31], the isoelectronic S doping compound has smaller μ 0 H c1 (0)s, as summarized in table 4.…”

Dioxirane‐Based Stereoselective and Oxidative Transformations

“…[62][63][64][65][66] Sulfoxides have myriads of applications in asymmetric synthesis, [67,68] drugs and biological studies. [68][69][70] Although the asymmetric oxidations of sulfides to sulfoxides are carried out using various methods, [70][71][72][73][74][75][76][77] the employment of dioxiranes for such oxidation offers transition metal-free green [78,79] synthetic protocol. It is worth mentioning that the treatment of a highly functionalized chiral sulfide with a strong oxidant can result in unwanted side reactions leading to unexpected products with a low yield of the desired sulfoxide.…”

Recent Developments on the Synthesis of Sulfoxides via Sulfenate Anions

“…8 Additionally, the reader is directed to other noteworthy review articles, wherein the synthesis of sulfoxides involving sulfenate anions is discussed. 9,10 It is also important to note that the utilization of sulfenate anions as organocatalysts represents another burgeoning area of research that has been pioneered by the Walsh group. 11…”