Electrically Programmable Correlated Topology and Magnetism in a Moir\'e Trilayer

Abstract

Strong electron-electron interactions underlie a wide range of quantum many-body phenomena, including magnetism, superconductivity, and charge fractionalization. A central goal is to achieve in situ control over lattice geometry, bandwidth, and band topology within a single platform. Here we realize such an electrically programmable quantum many-body system in an alternating twisted trilayer MoTe$_2$, where an out-of-plane displacement field continuously modifies the layer polarization, effective lattice, and topology of the moir\'e bands. At zero displacement field, the system realizes a triangular lattice hosting a correlated insulator at one hole per moir\'e unit cell ($\nu = -1$). Doping this state produces strongly asymmetric magnetic responses: double-exchange-like ferromagnetism for $|\nu| > 1$, and signatures of spin polarons and antiferromagnetism for $|\nu| < 1$. At large displacement field, interlayer hybridization reconstructs the electronic structure into a honeycomb lattice with a flat Chern band, supporting integer and fractional Chern insulators. Magneto-optical measurements further reveal the signatures of gap closure and Landau-level formation from a spin-polarized Fermi surface near the crossover between the two regimes. These results establish a unified, electrically tunable platform in which correlated magnetism and topological states emerge from a single controllable band structure.