Moiré Topological Insulator Double-Bilayers

Two-dimensional moiré materials in which opposite valleys have moiré bands with opposite Chern numbers are topological insulators (MTIs) at even integer band filling factors ν and, when bands are narrow, Chern insulators at odd integer ν. Double MTI's are a promising new platform for tunable strongly-interacting topological matter. We present a numerical exact diagonalization study of the properties of twisted MoTe₂ double-hombobilayers at total filling factor ν=1. We predict that the ground state of the bilayer is an exciton condensate when the two layers are populated by the same valley, and an inhomogenous state consisting of layer-polarized stripe domains separated by topological edge channels when the two layers are populated by opposite valleys. I will discuss expected hysteretic properties as a function of both external magnetic fields and gate-induced displacement fields.