Surface-Limited Superconducting Phase Transition on 1 T-TaS<sub>2</sub>.
basic_science · Level V
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- Record sourced from PubMed, PMID 30403840.
- Also identified by DOI 10.1021/acsnano.8b07379.
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Abstract
Controlling superconducting phase transition on a two-dimensional (2D) material is of great fundamental and technological interest from the viewpoint of making 2D resistance-free electronic circuits. Here, we demonstrate that a 1 T-to-2 H phase transition can be induced on the topmost monolayer of bulk (<100 nm thick) 1 T-TaS<sub>2</sub> by thermal annealing. The monolayer 2 H-TaS<sub>2</sub> on bulk 1 T-TaS<sub>2</sub> exhibits a superconducting transition temperature ( T<sub>c</sub>) of 2.1 K, which is significantly enhanced compared to that of bulk 2 H-TaS<sub>2</sub>. Scanning tunneling microscopy measurements reveal a 3 × 3 charge density wave (CDW) in the phase-switched monolayer at 4.5 K. The enhanced T<sub>c</sub> is explained by the suppressed 3 × 3 CDW and a charge-transfer doping from the 1 T substrate. We further show that the monolayer 2 H-TaS<sub>2</sub> could be switched back to 1 T phase by applying a voltage pulse. The observed surface-limited superconducting phase transition offers a convenient way to prepare robust 2D superconductivity on bulk 1 T-TaS<sub>2</sub> crystal, thereby bypassing the need to exfoliate monolayer samples.