Polar Vortex Superstructure and Its Coupling with Correlated Electrons in Quasiperiodic Moire Crystal

TL;DR

This paper reports the discovery of a gate-tunable polar vortex superstructure in twisted bilayer graphene aligned with hexagonal boron nitride, revealing new ways to engineer nanoscale polar and correlated quantum states in moiré materials.

Contribution

It demonstrates the formation of a polar vortex superstructure from moiré pattern reconstruction and its interaction with electron correlations, a novel approach in van der Waals heterostructures.

Findings

Reconstructed moiré patterns induce a polar vortex superstructure.

The polar field is gate-tunable, showing unconventional sliding and screening.

Interaction with electron correlations modulates quantum states.

Abstract

Nanoscale polar structures are significant for understanding polarization processes in low-dimensional systems and hold potential for developing high-performance electronics. Here, we demonstrate a polar vortex superstructure arising from the reconstructed moir\'e patterns in twisted bilayer graphene aligned with hexagonal boron nitride. Scanning tunneling microscopy reveals spatially modulated charge polarization, while theoretical simulations indicate that the in-plane polarization field forms an array of polar vortices. Notably, this polar field is gate-tunable, exhibiting an unconventional gate-tunable polar sliding and screening process. Moreover, its interaction with electron correlations in twisted bilayer graphene leads to modulated correlated states. Our findings establish moir\'e pattern reconstruction as a powerful strategy for engineering nanoscale polar structures and emergent quantum phases in van der Waals materials.