Magnetic moiré surface states and flat chern band in topological insulators

Abstract

We theoretically study the effect of magnetic moiré superlattice on the topological surface states by introducing a continuum model of Dirac electrons with a single Dirac cone moving in the time-reversal symmetry breaking periodic pontential. The Zeeman-type moiré potentials generically gap out the moiré surface Dirac cones and give rise to isolated flat Chern minibands with Chern number $\pm 1$. This result provides a promising platform for realizing the time-reversal breaking correlated topological phases. In a $C_6$ periodic potential, when the scalar $U_0$ and Zeeman ${\Delta }_1$ moiré potential strengths are equal to each other, we find that energetically the first three bands of $\Gamma$-valley moiré surface electrons are non-degenerate and realize i) an $s$-orbital model on a honeycomb lattice, ii) a degenerate $p_x,p_y$-orbitals model on a honeycomb lattice, and iii) a hybridized $s{d}^2$-orbital model on a kagome lattice, where moiré surface Dirac cones in these bands emerge. When $U_0\ne {\Delta }_1$, the difference between the two moiré potential serves as an effective spin-orbit coupling and opens a topological gap in the emergent moiré surface Dirac cones.

arXiv comment7 pages, 4 figures

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• Designer Meron Lattice on the Surface of a Topological Insulator
• Magic angle conditions for twisted 3D topological insulators
• Kagome and honeycomb flat bands in moiré graphene
• Isolated nearly flat higher Chern band in monolayer transition metal trihalides
• Electrically tunable high-Chern-number quasiflat bands in twisted antiferromagnetic topological insulators
• Anisotropic moiré band flattening in twisted bilayers of M-valley MXenes
• Topological phase transition from periodic edge states in moiré superlattices
• Twisted Type-II Rashba Homobilayer: A Platform for Tunable Topological Flat Bands
• Orbital Description of Landau Levels