Title: Topological Electron Crystals in a Mass-Asymmetric Electron-Hole Bilayer

Abstract: Moiré superlattices have become a standard route to realizing correlated and crystalline electronic phases in two-dimensional materials by quenching kinetic energy. In this talk, I will describe a different mechanism for generating topological electron crystals based on interlayer charge transfer rather than moiré engineering.

Our platform is a heterostructure consisting of bilayer graphene and a Mott insulator. Charge transfer between the layers leads to a charge-neutral, mass-asymmetric electron-hole bilayer, where itinerant carriers in bilayer graphene are attractively coupled to heavy, localized carriers in a flat Hubbard band. In the dilute heavy-fermion limit, this system supports a remarkably rich set of electron crystal phases, including triangular, honeycomb, and Kagome crystals.

A key result is that the nonlocal nature of bilayer graphene wave functions strongly modifies the real-space charge profile, which in turn stabilizes these unconventional crystalline orders at intermediate interlayer attraction. The resulting phases carry distinct Hall responses and topological characteristics, opening a route to crystalline topology beyond the conventional moiré setting. I will present the phase diagram, explain the role of quantum geometry, and discuss possible experimental platforms.