Quasi-two-dimensional anisotropic superconductivity in Li-intercalated 2H-TaS₂

Superconductivity in two-dimensional (2D) materials has sparked great interest due to the emergence of various novel quantum phenomena. Recent experimental studies of 2D superconductivity in anisotropic layered materials propose both conventional and unconventional electron pairing. In this series, layered transition metal dichalcogenides (TMDs) are an intriguing class of materials which are the potential candidates to realise Ising superconductivity, spin-valley coupling, quantum spin hall effect, and non-trivial topologically protected band structure. Chemical doping or intercalation in such materials provides a suitable way to tune the interlayer coupling and thereby tune dimensionality.

In this work, we have investigated the enhanced superconductivity in 2H-TaS₂ by Li intercalation and demonstrated modified superconducting properties of parent compound 2H-TaS₂ after intercalation. The magnetisation, resistivity, and specific heat measurement of single crystals confirmed weakly coupled bulk anisotropic superconductivity having transition temperature at T_c ~ 3.3(1) K. Moreover, the cusp-like feature in angle-dependent magnetotransport measurement and the appearance of Berezinskii-Kosterlitz-Thouless (BKT) phase transition in bulk crystal Li_xTaS₂ suggested the quasi-2D nature of superconductivity. These findings suggest the weakening of interlayer coupling by Li intercalation. Moreover, the readily cleavable nature of 2H- Li_xTaS₂ promotes the thickness-dependent measurement and opens a door towards the more pronounced two-dimensional nature with enhanced spin-orbit coupling. There are very few studies in intercalated materials where BKT transition is observed, which makes Li_xTaS₂ a valuable candidate for understanding the superconductivity with BKT mechanism and providing a new insight towards the intercalated materials.