Superconductivity protected by spin-valley locking in ion-gated MoS2

Yu Saito, Yasuharu Nakamura, Mohammad Saeed Bahramy, Yoshimitsu Kohama, Jianting Ye, Yuichi Kasahara, Yuji Nakagawa, Masaru Onga, Masashi Tokunaga, Tsutomu Nojima, Youichi Yanase, Yoshihiro Iwasa

Research output: Contribution to journalArticle

196 Citations (Scopus)

Abstract

Symmetry-breaking has been known to play a key role in non-centrosymmetric superconductors with strong spin-orbit interactions (SOIs; refs,). The studies, however, have been so far mainly focused on a particular type of SOI, known as the Rashba SOI (ref.), whereby the electron spin is locked to its momentum at a right-angle, thereby leading to an in-plane helical spin texture. Here we discuss electric-field-induced superconductivity in molybdenum disulphide (MoS 2), which exhibits a fundamentally different type of intrinsic SOI, manifested by an out-of-plane Zeeman-type spin polarization of energy valleys. We find an upper critical field of approximately 52 T at 1.5 K, which indicates an enhancement of the Pauli limit by a factor of four as compared to that in centrosymmetric conventional superconductors. Using realistic tight-binding calculations, we reveal that this unusual behaviour is due to an inter-valley pairing that is symmetrically protected by Zeeman-type spin-valley locking against external magnetic fields. Our study sheds light on the interplay of inversion asymmetry with SOIs in confined geometries, and its role in superconductivity.

Original languageEnglish
Pages (from-to)144-149
Number of pages6
JournalNature Physics
Volume12
Issue number2
DOIs
Publication statusPublished - 2016 Feb 2

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    Saito, Y., Nakamura, Y., Bahramy, M. S., Kohama, Y., Ye, J., Kasahara, Y., Nakagawa, Y., Onga, M., Tokunaga, M., Nojima, T., Yanase, Y., & Iwasa, Y. (2016). Superconductivity protected by spin-valley locking in ion-gated MoS2. Nature Physics, 12(2), 144-149. https://doi.org/10.1038/nphys3580