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

Bibliographic Details
Title:	Superconductivity protected by spin-valley locking in ion-gated MoS2
Authors:	Saito, Yu, Nakamura, Yasuharu, Bahramy, Mohammad Saeed, Kohama, Yoshimitsu, Ye, Jianting, Kasahara, Yuichi, Nakagawa, Yuji, Onga, Masaru, Tokunaga, Masashi, Nojima, Tsutomu, Yanase, Youichi, Iwasa, Yoshihiro
Source:	Nature Physics 12 (2), 144-149 (2016)
Publication Year:	2015
Collection:	Condensed Matter
Subject Terms:	Condensed Matter - Superconductivity, Condensed Matter - Materials Science
More Details:	Symmetry-breaking has been known to play a key role in noncentrosymmetric superconductors with strong spin-orbit-interaction (SOI). The studies, however, have been so far mainly focused on a particular type of SOI, known as Rashba SOI, whereby the electron spin is locked to its momentum at a right-angle, thereby leading to an in-planar helical spin texture. Here we discuss electric-field-induced superconductivity in molybdenum disulphide (MoS2), 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 a new light on the interplay of inversion asymmetry with SOI in confined geometries, and its unprecedented role in superconductivity. Comment: 37 pages, 11 figures, http://meetings.aps.org/Meeting/MAR15/Session/G11.11
Document Type:	Working Paper
DOI:	10.1038/nphys3580
Access URL:	http://arxiv.org/abs/1506.04146
Accession Number:	edsarx.1506.04146
Database:	arXiv

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