Orbital-selective two-dimensional superconductivity in 2H−NbS2

Xiangyu Bi; Zeya Li; Junwei Huang; Feng Qin; Caorong Zhang; Zian Xu; Ling Zhou; Ming Tang; Caiyu Qiu; Peizhe Tang; Toshiya Ideue; Tsutomu Nojima; Yoshihiro Iwasa; Hongtao Yuan

doi:10.1103/PhysRevResearch.4.013188

Orbital-selective two-dimensional superconductivity in 2H−NbS2

Xiangyu Bi, Zeya Li, Junwei Huang, Feng Qin, Caorong Zhang, Zian Xu, Ling Zhou, Ming Tang, Caiyu Qiu, Peizhe Tang, Toshiya Ideue, Tsutomu Nojima, Yoshihiro Iwasa, Hongtao Yuan

DOI 10.1103/PhysRevResearch.4.013188 · Physical Review Research

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Abstract

Orbital-selective superconductivity is crucial for understanding the pairing mechanism for multiband superconductors. Atomic d orbitals with anisotropic spatial extension can directly determine the energy dispersion of subbands with two-dimensional (2D) or three-dimensional (3D) nature in band structure. Theoretically, owing to the coexistence of these 2D and 3D subbands, the orbital-selective superconductivity can exhibit band-dependent dimensionality in multiband superconductors. However, to experimentally confirm this orbital-selective 2D superconductivity remains challenging and elusive. Herein, based on angle-dependent upper critical magnetic field on 2H−NbS2 flakes, we observe a cusp peak associated with a 2D superconducting subband from the dxy and dx2−y2 orbitals of Nb atoms, and a round peak related to a 3D subband, directly confirming the existence of intrinsic 2D superconductivity in 2H−NbS2 thick flake and its orbital-selective superconducting nature. The 2D superconductivity remains robust under large electric current or high pressure. Such observations shed light on the orbital-selective pairing mechanism and resulting band-dependent dimensionality for multiband superconductors.