Superconductivity from spin fluctuations and long-range interactions in magic-angle twisted bilayer graphene

Abstract

Magic-angle twisted bilayer graphene (MATBG) has been extensively explored both theoretically and experimentally as a suitable platform for a rich and tunable phase diagram that includes ferromagnetism, charge order, broken symmetries, and unconventional superconductivity. In this work, we investigate the intricate interplay between long-range electron-electron interactions, spin fluctuations, and superconductivity in MATBG. By employing a low-energy model for MATBG that captures the correct shape of the flat bands, we explore the effects of short- and long-range interactions on spin fluctuations and their impact on the superconducting (SC) pairing vertex in the Random Phase Approximation (RPA). We find that the SC state is notably influenced by the strength of long-range Coulomb interactions. Interestingly, our RPA calculations indicate that there is a regime where the system can traverse from a magnetic phase to the SC phase by \emph{increasing} the relative strength of long-range interactions compared to the on-site ones. These findings underscore the relevance of electron-electron interactions in shaping the intriguing properties of MATBG and offer a pathway for designing and controlling its SC phase.

Revised and expanded version. 11 pages, 7 figures

References in corpus (6)

• Near-degeneracy of several pairing channels in multiorbital models for the Fe-pnictides
• The crucial role of atomic corrugation on the flat bands and energy gaps of twisted bilayer graphene at the "magic angle" $\theta \sim 1.08^{\circ }$
• Neutron and ARPES Constraints on the Couplings of the Multiorbital Hubbard Model for the Pnictides
• RPA Analysis of a Two-orbital Model for the BiS2-based Superconductors
• Competing Pairing Symmetries in a Generalized Two-Orbital Model for the Pnictides
• Identification of superconducting pairing symmetry in twisted bilayer graphene using in-plane magnetic field and strain

Cited by in corpus (3)

• Superconductivity and pair density waves from nearest-neighbor interactions in frustrated lattice geometries
• The extended Hubbard model on a honeycomb lattice
• Onset of spin-valley order and Stoner boundaries in twisted WSe${}_2$