Title | An unusual continuous paramagnetic-limited superconducting phase transition in 2D NbSe . |
Publication Type | Journal Article |
Year of Publication | 2018 |
Authors | Sohn, E, Xi, X, He, W-Y, Jiang, S, Wang, Z, Kang, K, Park, J-H, Berger, H, Forró, L, Law, KTuen, Shan, J, Mak, KFai |
Journal | Nat Mater |
Volume | 17 |
Issue | 6 |
Pagination | 504-508 |
Date Published | 2018 06 |
ISSN | 1476-1122 |
Abstract | Time reversal and spatial inversion are two key symmetries for conventional Bardeen-Cooper-Schrieffer (BCS) superconductivity . Breaking inversion symmetry can lead to mixed-parity Cooper pairing and unconventional superconducting properties. Two-dimensional (2D) NbSe has emerged as a new non-centrosymmetric superconductor with the unique out-of-plane or Ising spin-orbit coupling (SOC). Here we report the observation of an unusual continuous paramagnetic-limited superconductor-normal metal transition in 2D NbSe. Using tunelling spectroscopy under high in-plane magnetic fields, we observe a continuous closing of the superconducting gap at the upper critical field at low temperatures, in stark contrast to the abrupt first-order transition observed in BCS thin-film superconductors. The paramagnetic-limited continuous transition arises from a large spin susceptibility of the superconducting phase due to the Ising SOC. The result is further supported by self-consistent mean-field calculations based on the ab initio band structure of 2D NbSe. Our findings establish 2D NbSe as a promising platform to explore novel spin-dependent superconducting phenomena and device concepts , such as equal-spin Andreev reflection and topological superconductivity. |
DOI | 10.1038/s41563-018-0061-1 |
Alternate Journal | Nat Mater |
PubMed ID | 29713039 |