Tunable interlayer charge-transfer states in MoSe₂/WS₂ moiré superlattices

Moiré superlattices formed by transition metal dichalcogenide (TMD) heterobilayers provide a versatile platform to study strongly correlated electronic, excitonic, and magnetic phenomena in solids. In particular, angle-aligned MoSe₂/WS₂ heterobilayers with a switchable type-I/type-II band alignment and strong strain reconstruction are predicted to host rich correlated spin and charge physics interplayed with a vertical electric field. However, conventional transport methods remain to be challenging to access such correlated electronic and magnetic states in electron-doped TMD moiré systems. Here, we report a systematic study of the interlayer charge-transfer states and their dynamics in the 0°- and 60°-aligned electron-doped MoSe₂/WS₂ moiré superlattices using optical spectroscopical methods. By investigating the layer-resolved optical reflectance of the moiré excitations at different electric fields, we reveal multiple charge-ordered states in an integer filling factor sequence ν=1 to 4, associated with their interlayer charge transfer cascades near the type-I to type-II transition boundary. Furthermore, at ν=2, a robust pseudospin of the layer-switchable charge coupled with the vertical electric field can emerge, leading to an Ising ferromagnetic ground state. With an AC-modulated electrical-optical readout, we directly probe the pseudospin magnetization hysteresis and studied its ferromagnetic domain nucleation dynamics on a effective honeycomb lattice. Our results provide a comprehensive understanding of the correlated charge-transfer states in electron-doped MoSe₂/WS₂ moiré superlattices at integer fillings and demonstrate their high tunability for exploring emergent quantum many-body physics.