Non-volatile control of topological phase transition in an asymmetric ferroelectric In2Te2S monolayer

S monolayer has two asymmetric polarized states, which are characterized by a metal and semiconductor, respectively. Importantly, as the spin-orbit coupling is included, a band gap (50.4 meV) is created in the metallic state, resulting in a non-trivial topological phase. Thus, it proves to be a feasible method to engineer non-volatile FE control of topological order in a single-phase system. We also demonstrate the underlying physical mechanism of topological phase transition, which is unveiled to be related to the weakened intrinsic electric field resulting from charge transfer. These interesting results provide a general way to design asymmetric FE materials and shed light on their potential application in non-volatile multifunctional devices.