A scalable network model for electrically tunable ferroelectric domain structure in twistronic bilayers of two-dimensional semiconductors

TL;DR

This paper introduces a network model to describe and predict the tunable ferroelectric domain structures in twisted bilayer 2D semiconductors under electric fields, revealing a transition in the domain wall network topology.

Contribution

It develops a multiscale, string-theory-like model for ferroelectric domain networks in moiré structures, capturing their electric field-induced topological transition.

Findings

Identifies a threshold electric field for domain wall network transition.

Describes a qualitative change from partial to screw dislocation-like domain walls.

Provides a parametrized model for ferroelectric domain tunability.

Abstract

Moir\'e structures in small-angle-twisted bilayers of two-dimensional semiconductors with a broken-symmetry interface form arrays of ferroelectric domains with periodically alternating out-of-plane polarization. Here, we propose a network theory for the tunability of such FE domain structure by applying an electric field perpendicular to the 2D crystal. Using multiscale analysis, we derive a fully parametrized string-theory-like description of the domain wall network and show that it undergoes a qualitative change, after the arcs of partial dislocation like domain walls merge (near the network nodes) into streaks of perfect screw dislocations, which happens at a threshold displacement field dependent on the DWN period.