• 文献标题:   Unconventional topological superconductivity and phase diagram for an effective two-orbital model as applied to twisted bilayer graphene
  • 文献类型:   Article
  • 作  者:   FIDRYSIAK M, ZEGRODNIK M, SPALEK J
  • 作者关键词:  
  • 出版物名称:   PHYSICAL REVIEW B
  • ISSN:   2469-9950 EI 2469-9969
  • 通讯作者地址:   Jagiellonian Univ
  • 被引频次:   24
  • DOI:   10.1103/PhysRevB.98.085436
  • 出版年:   2018

▎ 摘  要

We consider the superconducting and Mott-insulating states for twisted bilayer graphene, modeled as a two-narrow-band system of electrons with appreciable intra-atomic Coulomb interactions. The interaction induces kinetic exchange which leads to real space, either triplet- or singlet-spin pairing, in direct analogy to heavy fermions and high-temperature superconductors. By employing the statistically consistent Gutzwiller method, we construct explicitly the phase diagram as a function of electron concentration for the spin-triplet d(x2-y2) + id(xy) paired case, as well as determine the topological edge states. The model reproduces principal features observed experimentally in a semi-quantitative manner. The essential role of electronic correlations in driving both the Mott-insulating and superconducting transitions is emphasized. The transformation of the spin-triplet state into its spin-singlet analog is also analyzed, as well as the appearance of the phase-separated superconducting+Mott-insulating state close to the half-filling.