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

Abstract

We report the path from the charge density wave (CDW)-bearing superconductor CuIr2Te4 to the metal insulator transition (MIT)-bearing compound CuIr2S4 by chemical alloying with the gradual substitution of S for Te. The evolution of structural and physical properties of the CuIr2Te4-x S x (0 ≤ x ≤ 4) polycrystalline system is systemically examined. The X-ray diffraction (XRD) results imply CuIr2Te4-xS x (0 ≤ x ≤ 0.5) crystallizes in a NiAs defected trigonal structure, whereas it adapts to the cubic spinel structure for 3.6 ≤ x ≤ 4 and it is a mixed phase in the doping range of 0.5 < x < 3.6. Unexpectedly, the resistivity and magnetization measurements reveal that small-concentration S substitution for Te can suppress the CDW transition, but it reappears around x = 0.2, and the CDW transition temperature enhances clearly as x augments for 0.2 ≤ x ≤ 0.5. Besides, the superconducting critical temperature (Tc) first increases with S doping content and then decreases after reaching a maximum Tc = 2.82 K for CuIr2Te3.85S0.15. MIT order has been observed in the spinel region (3.6 ≤ x ≤ 4) associated with TMI increasing with x increasing. Finally, the rich electronic phase diagram of temperature versus x for this CuIr2Te4-x S x system is assembled, where the superconducting dome is associated with the suppression and re-emergence of CDW as well as MIT states at the end upon sulfur substitution in the CuIr2Te4-x S x chalcogenides.

Evidence of unconventional pairing in the quasi-two-dimensional CuIr2−xRuxTe4 superconductor

“…Then, above 1.2 GPa, where the resistive hump becomes more evident, it starts to saturate. Such behavior is consistent with previous chemical-pressure studies on CuIr 2 Te 4 , indicating that both S-Te and Se-Te substitutions favor the CDW order [46,47]. Figure 10 shows the low-T (below 4 K) electrical resistivity and ac susceptibility collected at various applied pressures.…”

“…To prove such a scenario, it would be interesting to investigate the evolution of the superconducting pairing in CuIr 2 Te 4 under applied pressure, e.g., via TF-μSR measurements under pressure. Alternatively, TF-μSR measurements on CuIr 2 Te 4−x (Se, S) x , where multiple CDW phases are known to coexist with SC [46,47], would also provide important hints on the superconducting pairing.…”

Structure, electrical and thermal properties of single-crystal BaCuGdTe3

“…45 At the lowest measured temperatures dρ/dT > 0 indicating that the residual resistivity is not yet reached. Nevertheless, the relatively high residual resistance ratio (RRR ≈ 5) is comparable to that reported for single crystal metallic clathrate compositions as well as other ternary and quaternary chalcogenides, [46][47][48][49][50][51][52] and indicative of a good quality single crystal. We also considered the possibility that defects may affect the transport properties; however, our single crystal structure refinements show no fractional occupancy on any of the crystallographic positions.…”