Alternating Superconducting and Charge Density Wave Monolayers within Bulk 6R-TaS<sub>2</sub>.

Achari, Amritroop; Bekaert, Jonas; Sreepal, Vishnu; Orekhov, Andrey; Kumaravadivel, Piranavan; Kim, Minsoo; Gauquelin, Nicolas; Balakrishna Pillai, Premlal et al. · Nano Lett · 2022

basic_science · Level V

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Abstract

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 TaS<sub>2</sub> monolayers interlayered with 1T TaS<sub>2</sub> monolayers displaying charge density waves (CDW). This bulk vdW heterostructure is created by phase transition of 1T-TaS<sub>2</sub> to 6R at 800 °C in an inert atmosphere. Its superconducting transition (<i>T</i><sub>c</sub>) is found at 2.6 K, exceeding the <i>T</i><sub>c</sub> of the bulk 2H phase. Using first-principles calculations, we argue that the coexistence of superconductivity and CDW within 6R-TaS<sub>2</sub> 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.