Realization of Polytype Heterostructures via Delicate Structural Transitions from a Doped Mott Insulator

Transition-metal dichalcogenides hosting multiple competing structural and electronic phases are thus ideal platforms for constructing polytype heterostructures with emergent quantum properties. However, controlling phase transitions to form diverse heterostructures inside a single crystal remains challenging. In this study, we realize vertical/lateral polytype heterostructures in a hole-doped Mott insulator via thermal annealing-induced structural transitions. Raman spectroscopy, atomic force microscopy and scanning Kelvin probe force microscopy confirm the coexistence of T-H polytype heterostructures. Atomic-scale scanning tunneling microscopy/spectroscopy measurements reveal the transparent effect in 1H/1T vertical heterostructures, where positive bias voltage induces in a pronounced superposition of the \sqrt13 \times \sqrt13 CDW of the 1T-layer on the 1H-layer. By systematically comparing the 1T/1H and 1T/1T interfaces, we demonstrate that the metallic 1H-layer induces a Coulomb screening effect on the 1T-layer, suppressing the formation of CDW domain walls and forming more ordered electronic states. These results clarify the interfacial coupling between distinct quantum many-body phases and establish a controllable pathway for constructing two-dimensional polytype heterostructures with tunable electronic properties.