Ferroelectric switching at symmetry-broken interfaces by local control of dislocation networks

TL;DR

This study demonstrates local control of ferroelectric domains in a twisted WS2 bilayer at room temperature, revealing mechanisms for reversible polarization switching crucial for future 2D ferroelectric devices.

Contribution

It introduces a method to manipulate ferroelectric domains in 2D materials using a scanning tunneling microscope, with insights into domain evolution mechanisms.

Findings

Reversible ferroelectric domain control at room temperature.

Identification of elastic bending and screw dislocation formation regimes.

Reversible polarization restoration via perfect screw dislocations.

Abstract

Semiconducting ferroelectric materials with low energy polarisation switching offer a platform for next-generation electronics such as ferroelectric field-effect transistors. Ferroelectric domains at symmetry-broken interfaces of transition metal dichalcogenide films provide an opportunity to combine the potential of semiconducting ferroelectrics with the design flexibility of two-dimensional material devices. Here, local control of ferroelectric domains in a marginally twisted WS2 bilayer is demonstrated with a scanning tunneling microscope at room temperature, and their observed reversible evolution understood using a string-like model of the domain wall network. We identify two characteristic regimes of domain evolution: (i) elastic bending of partial screw dislocations separating smaller domains with twin stacking and (ii) formation of perfect screw dislocations by merging pairs of primary domain walls. We also show that the latter act as the seeds for the reversible restoration of the inverted polarisation. These results open the possibility to achieve full control over atomically thin semiconducting ferroelectric domains using local electric fields, which is a critical step towards their technological use.