Highly tunable moir\'e superlattice potentials in twisted hexagonal boron nitrides

TL;DR

This paper demonstrates highly tunable moiré superlattice potentials in twisted hexagonal boron nitride, enabling precise control over ferroelectric domains and strain, with potential applications in quantum materials and twistronics.

Contribution

It introduces a method to realize and visualize tunable moiré superlattices in twisted hBN, including in-situ manipulation of potential strength via femtosecond laser irradiation.

Findings

Achieved uniform moiré structures with precise control.

Demonstrated multi-level ferroelectric domains and anisotropic moiré patterns.

Showed in-situ optical control of moiré potential using femtosecond laser.

Abstract

Moir\'e superlattice of twisted hexagonal boron nitride (hBN) has emerged as an advanced atomically thin van der Waals interfacial ferroelectricity platform. Nanoscale periodic ferroelectric moir\'e domains with out-of-plane potentials in twisted hBN allow the hosting of remote Coulomb superlattice potentials to adjacent two-dimensional materials for tailoring strongly correlated properties. Therefore, the new strategies for engineering moir\'e length, angle, and potential strength are essential for developing programmable quantum materials and advanced twistronics applications devices. Here, we demonstrate the realization of twisted hBN-based moir\'e superlattice platforms and visualize the moir\'e domains and ferroelectric properties using Kelvin probe force microscopy. Also, we report the KPFM result of regular moir\'e superlattice in the large area. It offers the possibility to reproduce uniform moir\'e structures with precise control piezo stage stacking and heat annealing. We demonstrate the high tunability of twisted hBN moir\'e platforms and achieve cumulative multi-ferroelectric polarization and multi-level domains with multiple angle mismatched interfaces. Additionally, we observe the quasi-1D anisotropic moir\'e domains and show the highest resolution analysis of the local built-in strain between adjacent hBN layers compared to the conventional methods. Furthermore, we demonstrate in-situ manipulation of moir\'e superlattice potential strength using femtosecond pulse laser irradiation, which results in the optical phonon-induced atomic displacement at the hBN moir\'e interfaces. Our results pave the way to develop precisely programmable moir\'e superlattice platforms and investigate strongly correlated physics in van der Waals heterostructures.