Dualistic correlated phases induced by interlayer sliding in few layer Ta2NiS5

Interlayer sliding in van der Waals materials has recently attracted great interest for tuning correlated quantum states. In this work, we report two dualistic naturally coexisting phases in few layer dimetal chalcogenide Ta ₂ NiS ₅ (TNS) induced by interlayer sliding, both metallic at room temperature but evolve into distinct correlated phases at low temperature. Importantly, in correlated phase I, we have uncovered previously overlooked exciton insulator (EI), in which the strong electric-field induced exciton dissociation and metallization behaviors have been observed. In the correlated phase II, three distinct critical points are identified by thermal induced current measurement, which is likely linked to the semi-metallic behavior with multi-electron and hole pockets. Furthermore, these two distinct correlated phases can be directly converted through temperature and AC electric-fields, offering a controllable and robust strategy for manipulating the quantum states in layered materials. Leveraging exciton dissociation in correlated phase I, we showcase an energy conversion device with record-high thermal induced current in the 10 10 µA level. These findings establish TNS as a promising platform to explore the fermionic pairing state and correlated quantum phases, and demonstrate that interlayer sliding can serve as an effective degree of freedom in tuning exotic quantum phases.