Tuning Ising superconductivity with layer and spin-orbit coupling in two-dimensional transition-metal dichalcogenides

Sergio C. de la Barrera; Michael R. Sinko; Devashish P. Gopalan; Nikhil Sivadas; Kyle L. Seyler; Kenji Watanabe; Takashi Taniguchi; Adam W. Tsen; Xiaodong Xu; Di Xiao; Benjamin M. Hunt

doi:10.1038/s41467-018-03888-4

arXiv · 1711.00468

Tuning Ising superconductivity with layer and spin-orbit coupling in two-dimensional transition-metal dichalcogenides

Sergio C. de la Barrera·Michael R. Sinko·Devashish P. Gopalan·Nikhil Sivadas·Kyle L. Seyler·Kenji Watanabe·Takashi Taniguchi·Adam W. Tsen·Xiaodong Xu·Di Xiao·Benjamin M. Hunt

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Abstract

Systems that simultaneously exhibit superconductivity and spin-orbit coupling are predicted to provide a route toward topological superconductivity and unconventional electron pairing, driving significant contemporary interest in these materials. Monolayer transition-metal dichalcogenide (TMD) superconductors in particular lack inversion symmetry, enforcing a spin-triplet component of the superconducting wavefunction that increases with the strength of spin-orbit coupling. In this work, we present an experimental and theoretical study of two intrinsic TMD superconductors with large spin-orbit coupling in the atomic layer limit, metallic 2H-TaS$_2$ and 2H-NbSe$_2$. For the first time in TaS$_2$, we investigate the superconducting properties as the material is reduced to a monolayer and show that high-field measurements point to the largest upper critical field thus reported for an intrinsic TMD superconductor. In few-layer samples, we find that the enhancement of the upper critical field is sustained by the dominance of spin-orbit coupling over weak interlayer coupling, providing additional platforms for unconventional superconducting states in two dimensions.

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Sergio C. de la Barrera, Michael R. Sinko, Devashish P. Gopalan, Nikhil Sivadas, Kyle L. Seyler, Kenji Watanabe, Takashi Taniguchi, Adam W. Tsen, Xiaodong Xu, Di Xiao, Benjamin M. Hunt. 2017-11-01. Tuning Ising superconductivity with layer and spin-orbit coupling in two-dimensional transition-metal dichalcogenides. https://doi.org/10.1038/s41467-018-03888-4

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