Alternating Superconducting and Charge Density Wave Monolayers within Bulk 6R-TaS2

Van der Waals (vdW) heterostructures continue to attract intense interest as a route of designing materials with novel properties that cannot be found in nature. Unfortunately, this approach is currently limited to only a few layers that can be stacked on top of each other. Here, we report a bulk vdW material consisting of superconducting 1H TaS₂ monolayers interlayered with 1T TaS₂ monolayers displaying charge density waves (CDW). This bulk vdW heterostructure is created by phase transition of 1T-TaS₂ to 6R at 800 °C in an inert atmosphere. Its superconducting transition (T_c) is found at 2.6 K, exceeding the T_c of the bulk 2H phase. Using first-principles calculations, we argue that the coexistence of superconductivity and CDW within 6R-TaS₂ stems from amalgamation of the properties of adjacent 1H and 1T monolayers, where the former dominates the superconducting state and the latter the CDW behavior.