Emerged charge-density wave featuring quasi-one-dimensional chains in Ta-intercalated bilayer TaS$_{2}$ with coexisting superconductivity

Abstract

Intercalation recent emerges as an effective way to manipulate ground-state properties and enrich quantum phase diagrams of layered transition metal dichalcogenides (TMDCs). In this work, focusing on fully Ta-intercalated bilayer TaS2 with a stoichiometry of Ta3S4, which has recently been experimentally synthesized, we computationally show the suppression of intrinsic 3 × 3 chargedensity wave (CDW) in bilayer TaS2 section, and emergence of a 2 × 1 CDW in intercalated Ta layer, based on first-principle calculations. The formation of the CDW in Ta3S4 is triggered by strong electron-phonon coupling (EPC) between d-like orbitals of intercalated Ta via the imaginary phonon modes at M point. A 2×1 CDW structure is identified, featuring quasi-one-dimensional Ta chains, attributable to the competition between CDW displacements associated with potential q CDW s. Superconductivity is found to coexist with the 2×1 CDW in Ta3S4, with an estimated superconducting transition temperature (Tc) of 3.0 K, slightly higher than that of the bilayer TaS2. The switch among the states without CDW, with 2×1 CDW, and with 2×2 CDW can be achieved in Ta3S4 by strains. Our work enriches quantum phase of TaS2, offers a candidate material to the study of the interaction between CDW and superconductivity, and highlights the intercalation as an effective way to tune the physical properties of layered materials.