Ferroelectric control of the Mott insulator-topological metal transition

Correlated and topological phases often coexist or compete in van der Waals materials, yet achieving an electrically switchable and reversible conversion between them remains a substantial challenge. Such control is crucial for understanding their interplay and enabling nonvolatile, low-power topological electronics. Here, we propose and demonstrate a polarization-controlled route to switch between Mott insulator and topological metal in ferroelectric-Mott heterostructures. In a-In₂Se₃/1T-NbSe₂, polarization reversal modulates interlayer coupling through out-ofplane orbital alignment. Downward polarization stabilizes Mott-insulating states with type-I band alignment, whereas upward polarization enhances interfacial hybridization, forms interlayer covalent-like quasi-bonding, and drives Γ-point band inversions. The resulting spin-split hybridized valleys penetrate the valence band, inducing a nontrivial topological state with intrinsic anomalous Hall conductivity of ~10² siemens per centimeter. The comparison with a-In₂Se₃/1T-TaSe₂ and a-In₂Se₃/1T-TaS₂ further identifies Γ-centered valleys and out-of-plane p_z-orbital coupling as key ingredients for polarization-switchable topology, providing a general design framework for electrically programmable correlated-topological integration in two-dimensional heterostructures.