Realization of polytype heterostructures via delicate structural transitions from a doped-Mott insulator

TL;DR

This study demonstrates the controlled creation of polytype heterostructures in doped-Mott insulators through thermal annealing, revealing how interfacial coupling influences electronic phases and enabling tunable quantum properties in 2D materials.

Contribution

It introduces a method to form diverse polytype heterostructures in a single crystal via thermal-annealing-induced structural transitions, advancing control over quantum phases in TMDs.

Findings

Confirmed coexistence of T-H polytype heterostructures using microscopy techniques.

Observed charge density wave superposition in 1H/1T heterostructures under bias.

Showed Coulomb screening effect of 1H-layer suppresses CDW domain walls.

Abstract

Transition metal dichalcogenides (TMDs) host multiple competing structural and electronic phases, making them an ideal platform for constructing polytype heterostructures with emergent quantum properties. However, controlling phase transitions to form diverse heterostructures inside a single crystal remains challenging. Here, we realize vertical/lateral polytype heterostructures in a hole-doped Mott insulator via thermal-annealing-induced structural transitions. Raman spectroscopy, atomic force microscopy (AFM) and scanning Kelvin probe force microscopy (SKPM) confirm the coexistence of T-H polytype heterostructures. Atomic-scale scanning tunneling microscopy/spectroscopy (STM/STS) measurements reveal the transparent effect in 1H/1T vertical heterostructures, where the charge density wave (CDW) of the underlying 1T-layer superposes on the top 1H-layer under positive bias. By systematically comparing 1T/1H and 1T/1T interfaces, we demonstrate that the metallic 1H-layer imposes 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.