Polar meron-antimeron networks in strained and twisted bilayers

TL;DR

This paper reveals that strained and twisted bilayers with broken inversion symmetry develop in-plane polarization components, forming topologically non-trivial meron-antimeron networks that could enable exploration of topological physics.

Contribution

It demonstrates the emergence of in-plane polarization and topological meron-antimeron networks in strained and twisted bilayers, expanding understanding of polarization effects in layered materials.

Findings

Polar domains form meron-antimeron networks with topological properties

In-plane polarization components are symmetry-determined

Different types of merons (Bloch and Ne9el) are identified in twisted and strained systems

Abstract

Out-of-plane polar domain structures have recently been discovered in strained and twisted bilayers of inversion symmetry broken systems such as hexagonal boron nitride. Here we show that this symmetry breaking also gives rise to an in-plane component of polarization, and the form of the total polarization is determined purely from symmetry considerations. The in-plane component of the polarization makes the polar domains in strained and twisted bilayers topologically non-trivial, forming a network of merons and antimerons (half-skyrmions and half-antiskyrmions). For twisted systems, the merons are of Bloch type whereas for strained systems they are of N\'eel type. We propose that the polar domains in strained or twisted bilayers may serve as a platform for exploring topological physics in layered materials and discuss how control over topological phases and phase transitions may be achieved in such systems.