摘要
The recent discovery of superconductivity in the twisted bilayer graphene has stimulated numerous theoretical proposals concerning its exact gap symmetry.Among them, the d + id or p + ip-wave was believed to be the most plausible solution.Here, considering that the superconductivity emerges near a correlated insulating state and may be induced by antiferromagnetic spin fluctuations, we apply the strong-coupling Eliashberg theory with both inter-and intraband quantum critical pairing interactions and discuss the possible gap symmetry in an effective low-energy four-orbital model.Our calculations reveal a nodeless s~±-wave as the most probable candidate for the superconducting gap symmetry in the experimentally relevant parameter range.This solution is distinctly different from previous theoretical proposals.It highlights the multi-gap nature of the superconductivity and puts the twisted bilayer graphene in the same class as the iron-pnictide,electron-doped cuprate, and some heavy fermion superconductors.
The recent discovery of superconductivity in the twisted bilayer graphene has stimulated numerous theoretical proposals concerning its exact gap symmetry.Among them, the d + id or p + ip-wave was believed to be the most plausible solution.Here, considering that the superconductivity emerges near a correlated insulating state and may be induced by antiferromagnetic spin fluctuations, we apply the strong-coupling Eliashberg theory with both inter-and intraband quantum critical pairing interactions and discuss the possible gap symmetry in an effective low-energy four-orbital model.Our calculations reveal a nodeless s~±-wave as the most probable candidate for the superconducting gap symmetry in the experimentally relevant parameter range.This solution is distinctly different from previous theoretical proposals.It highlights the multi-gap nature of the superconductivity and puts the twisted bilayer graphene in the same class as the iron-pnictide,electron-doped cuprate, and some heavy fermion superconductors.
作者
Zhe Liu
Yu Li
Yi-Feng Yang
刘哲;李宇;杨义峰(Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;University of Chinese Academy of Sciences. Beijing 100049, China;Songshan Lake Materials Laboratory, Dongguan 523808, China;Collaborative Innovation Center of Quantum Matter, Beijing 100190, China)
基金
Project supported by the National Key R&D Program of China(Grant No.2017YFA0303103)
the National Natural Science Foundation of China(Grant Nos.11774401 and 11522435)
the State Key Development Program for Basic Research of China(Grant No.2015CB921303)
the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB07020200)
the Youth Innovation Promotion Association of the Chinese Academy of Sciences
