Shear-Mode Raman Imaging of Ferroelectric Switching in Multilayer 3$R$-MoS$_2$

TL;DR

This study employs shear-mode Raman imaging to visualize ferroelectric switching in multilayer 3$R$-MoS$_2$, revealing domain wall behavior, polarization states, and the influence of boundaries on switching dynamics.

Contribution

It introduces shear-mode Raman imaging as a novel, noninvasive technique to study ferroelectric domain dynamics in multilayer 3$R$-MoS$_2$, highlighting the role of boundaries and pinning sites.

Findings

Domain walls can exist between specific layer pairs, causing partial stacking transformations.

Intermediate states exhibit widely varying dwell times due to pinning sites.

Characteristic boundary and domain-wall orientations, including a chiral direction, are identified.

Abstract

We use shear-mode Raman imaging to track ferroelectric switching in multilayer 3$R$-MoS$_2$. Within a single flake, mechanically segmented regions respond independently and follow distinct pathways. Partially polarized end states indicate that domain walls can reside between selected layer pairs, producing partial stacking transformations. The dwell time of intermediate states varies widely, indicating that pinning sites strongly influence the dynamics. Second-harmonic generation measurements further reveal three characteristic sample-boundary and domain-wall orientations, including a prevalent chiral direction near the zigzag-armchair bisector. These results provide a direct, noninvasive view of domain-wall-mediated switching in a prototypical sliding ferroelectric and identify pinning and exfoliation-created boundaries as key factors governing its dynamics.