Highly Tunable Moiré Superlattice Potentials in Twisted Hexagonal Boron Nitrides.

Moiré superlattice of twisted hexagonal boron nitride (hBN) has emerged as an advanced atomically thin van der Waals interfacial ferroelectricity platform. Nanoscale periodic ferroelectric moiré potentials in twisted hBN allow the hosting of remote Coulomb superlattice potentials to adjacent 2D materials. Therefore, the new strategies for engineering moiré length, angle, and potential strength are essential for developing programmable quantum materials. Here, it demonstrates the realization of twisted hBN-based moiré superlattice platforms and visualizes the moiré domains and ferroelectric properties using Kelvin probe force microscopy (KPFM). Also, the regular moiré superlattice in the large area is reported. It offers the possibility to reproduce uniform moiré structures with precise control piezo stage stacking and heat annealing. It demonstrates cumulative multi-ferroelectric polarization and multi-level domains with multiple angle mismatched interfaces. Additionally, it observes the quasi-1D anisotropic moiré domains and show the highest resolution analysis of the local built-in strain between adjacent hBN layers compared to the conventional methods. Furthermore, in-situ manipulation of moiré potential is demonstrated using femtosecond pulse laser, which results in the optical phonon-induced atomic displacement at the hBN moiré interfaces. The results pave the way to develop precisely programmable moiré superlattice platforms and investigate strongly correlated physics.