Ising pairing in superconducting NbSe2 atomic layers

Xiaoxiang Xi, Zefang Wang, Weiwei Zhao, Ju Hyun Park, Kam Tuen Law, Helmuth Berger, László Forró, Jie Shan, Kin Fai Mak

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336 Scopus citations

Abstract

The properties of two-dimensional transition metal dichalcogenides arising from strong spin-orbit interactions and valley-dependent Berry curvature effects have recently attracted considerable interest. Although single-particle and excitonic phenomena related to spin-valley coupling have been extensively studied, the effects of spin-valley coupling on collective quantum phenomena remain less well understood. Here we report the observation of superconducting monolayer NbSe 2 with an in-plane upper critical field of more than six times the Pauli paramagnetic limit, by means of magnetotransport measurements. The effect can be interpreted in terms of the competing Zeeman effect and large intrinsic spin-orbit interactions in non-centrosymmetric NbSe 2 monolayers, where the electron spin is locked to the out-of-plane direction. Our results provide strong evidence of unconventional Ising pairing protected by spin-momentum locking, and suggest further studies of non-centrosymmetric superconductivity with unique spin and valley degrees of freedom in the two-dimensional limit.

Original languageEnglish (US)
Pages (from-to)139-143
Number of pages5
JournalNature Physics
Volume12
Issue number2
DOIs
StatePublished - Feb 2 2016

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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    Xi, X., Wang, Z., Zhao, W., Park, J. H., Law, K. T., Berger, H., Forró, L., Shan, J., & Mak, K. F. (2016). Ising pairing in superconducting NbSe2 atomic layers. Nature Physics, 12(2), 139-143. https://doi.org/10.1038/nphys3538