Superconducting properties of van der Waals metal-rich subsulfide Nb$_{1.7}$Ta$_{3.3}$S$_2$

Abstract

Layered metal-rich subsulfides have become a promising area for exploring intriguing properties such as superconductivity, nontrivial topology, and charge density waves; however, despite their extraordinary potential, they have remained largely unexplored. We report a comprehensive analysis of a van der Waals layered metal-rich subsulfide, Nb$_{1.7}$Ta$_{3.3}$S$_2$, using a range of measuring techniques, including AC transport, magnetization, and specific heat. Our measurements confirm the occurrence of a type-II superconducting transition at a temperature of approximately $T_c$ = 3.64(1) K. Furthermore, specific heat measurements suggest weakly coupled, nodeless superconductivity.