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The natural bulk Van der Waals heterostructure compound 6R-TaS₂ consists of alternate stacking 1T- and 1H-TaS₂ monolayers, creating a unique system that incorporates charge-density-wave (CDW) order and superconductivity (SC) in distinct monolayers. Here, after confirming that the 2D nature of the lattice is preserved up to 8 GPa in 6R-TaS₂, we documented an unusual evolution of CDW and SC by conducting high-pressure electronic transport measurements. Upon compression, we observe a gradual suppression of CDW within the 1T layers, while the SC exhibits a dome-shaped behavior that terminates at a critical pressure P₂ around 2. 9 GPa. By taking account of the fact that the substantial suppression of SC is concomitant with the complete collapse of CDW order at P₂, we argue that the 6R-TaS₂ behaves like a stack of Josephson junctions and thus the suppressed superconductivity can be attributed to the weakening of Josephson coupling associated with the presence of CDW fluctuations in the 1T layers. Furthermore, the SC reversely enhances above P₂, implying the development of emergent superconductivity in the 1T layers after the melting of T-layer CDW orders. These results show that the 6R-TaS₂ not only provides a promising platform to explore emergent phenomena but also serves as a model system to study the complex interactions between competing electronic states.
Wang et al. (Mon,) studied this question.