Doping-induced quantum anomalous Hall crystals and topological domain walls

Doping carriers into a correlated quantum ground state offers a promising route to generate new quantum states. The recent advent of moir\'e superlattices provided a versatile platform with great tunability to explore doping physics in systems with strong interplay between strong correlation and nontrivial topology. Here we study the effect of electron doping in the quantum anomalous Hall insulator realized in a transition-metal dichalcogenide moir\'e superlattice at filling $\ensuremath{\nu}=1$, which can be described by the canonical Kane-Mele-Hubbard model. By solving the Kane-Mele-Hubbard model using an unrestricted real-space Hartree-Fock method, we find that doping generates quantum anomalous Hall crystals (QAHCs) and topological domain walls. In the QAHC, doping induces skyrmion spin textures, which host one or two electrons in each skyrmion as in-gap states. The skyrmions crystallize into a lattice, with the lattice parameter being tunable by the density of doped electrons. Remarkably, we find that the QAHC can survive even in the limit of vanishing Kane-Mele topological gap for a significant range of fillings. Furthermore, doping can also induce domain walls separating topologically distinct domains with different electron densities, hosting chiral localized modes.