The transition-metal-dichalcogenide family as a superconductor tuned by charge density wave strength.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39616172.
- Also identified by DOI 10.1038/s41467-024-54517-2 and PMC identifier 11608225.
- Licence recorded as CC BY-NC-ND.
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Abstract
In metallic transition metal dichalcogenides (TMDs), which remain superconducting down to single-layer thickness, the critical temperature T<sub>c</sub> decreases for Nb-based, and increases for Ta-based materials. This contradicting trend is puzzling, impeding the development of a unified theory. Here we study the thickness-evolution of superconducting tunneling spectra in TaS<sub>2 </sub>heterostructures. The upper critical field H<sub>c2</sub> is strongly enhanced towards the single-layer limit - following <math xmlns="http://www.w3.org/1998/Math/MathML"> <msub><mrow><mi>H</mi></mrow> <mrow><mi>c</mi> <mn>2</mn></mrow> </msub> <mo>∝</mo> <msubsup><mrow><mi>T</mi></mrow> <mrow><mi>c</mi></mrow> <mrow><mn>2</mn></mrow> </msubsup> </math> . The same ratio holds for the entire family of intrinsically metallic 2H-TMDs, covering 4 orders of magnitude in H<sub>c2</sub>. Using Gor'kov's theory, we calculate the suppression of T<sub>c</sub> by the competing charge density wave (CDW) order, which affects the quasiparticle density of states and the resulting T<sub>c</sub> and H<sub>c2</sub>. The latter is found to be universally enhanced by two orders of magnitude. Our results substantiate CDW as the key determinant factor limiting T<sub>c</sub> across the TMD family.