Antiferromagnetism and chiral d-wave superconductivity from an effective $t-J-D$ model for twisted bilayer graphene

Abstract

Starting from the strong-coupling limit of an extended Hubbard model, we develop a spin-fermion theory to study the insulating phase and pairing symmetry of the superconducting phase in twisted bilayer graphene. Assuming that the insulating phase is an anti-ferromagnetic insulator, we show that fluctuations of the anti-ferromagnetic order in the conducting phase can mediate superconducting pairing. Using a self-consistent mean-field analysis, we find that the pairing wave function has a chiral d-wave symmetry. Consistent with this observation, we show explicitly the existence of chiral Majorana edge modes by diagonalizing our proposed Hamiltonian on a finite-sized system. These results establish twisted bilayer graphene as a promising platform to realize topological superconductivity.

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Cited by in corpus (7)

• Superconductivity without insulating states in twisted bilayer graphene stabilized by monolayer WSe${}_2$
• High-$T_{\text{C}}$ Superconductivity Originating from Interlayer Coulomb Coupling in Gate-Charged Twisted Bilayer Graphene Moir$\acute{e}$ Superlattices
• Nematic insulator at charge neutrality in twisted bilayer graphene
• Moir{é} pattern assisted geometric resonant tunneling in disordered twisted bilayer graphene
• Magnon bands in twisted bilayer honeycomb quantum magnets
• Quantum Monte Carlo study of magnetism and chiral d+id-wave superconductivity in twisted bilayer graphene
• Magnetism of magic-angle twisted bilayer graphene