TY - JOUR
T1 - Superconductivity protected by spin-valley locking in ion-gated MoS2
AU - Saito, Yu
AU - Nakamura, Yasuharu
AU - Bahramy, Mohammad Saeed
AU - Kohama, Yoshimitsu
AU - Ye, Jianting
AU - Kasahara, Yuichi
AU - Nakagawa, Yuji
AU - Onga, Masaru
AU - Tokunaga, Masashi
AU - Nojima, Tsutomu
AU - Yanase, Youichi
AU - Iwasa, Yoshihiro
N1 - Funding Information:
We thank T. Gokuden for technical support, and M. Yoshida and K. Kikutake for fruitful discussions. Y.S. and Y. Nakamura were supported by the Japan Society for the Promotion of Science (JSPS) through a Research Fellowship for Young Scientists. This work was supported by Grant-in-Aid for Specially Promoted Research (no. 25000003) from JSPS and Grant-in Aid for Scientific Research on Innovative Areas (no. 22103004) from MEXT of Japan.
Publisher Copyright:
© 2016 Macmillan Publishers Limited.
PY - 2016/2/2
Y1 - 2016/2/2
N2 - 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.
AB - 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.
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U2 - 10.1038/nphys3580
DO - 10.1038/nphys3580
M3 - Article
AN - SCOPUS:84956644846
SN - 1745-2473
VL - 12
SP - 144
EP - 149
JO - Nature Physics
JF - Nature Physics
IS - 2
ER -