# Polar Coupling Enabled Nonlinear Optical Filtering at MoS$_2$/Ferroelectric Heterointerfaces

## TL;DR

This paper demonstrates a novel nonlinear optical filtering effect at MoS$_2$/ferroelectric heterointerfaces, controlled by interfacial polar alignment and domain structures, offering new avenues for reconfigurable nanoscale optical devices.

## Contribution

It reveals a new interfacial polar coupling mechanism in heterostructures that enables tunable nonlinear optical responses, distinct from charge, spin, or lattice interactions.

## Key findings

- Enhanced or quenched second harmonic generation at heterointerfaces.
- Polar domain structures modulate optical responses.
- Density functional theory explains the polar symmetry effects.

## Abstract

Complex oxide heterointerfaces and van der Waals heterostructures present two versatile but intrinsically different platforms for exploring emergent quantum phenomena and designing new functionalities. The rich opportunity offered by the synergy between these two classes of materials, however, is yet to be charted. Here, we report an unconventional nonlinear optical filtering effect resulting from the interfacial polar alignment between monolayer MoS$_2$ and a neighboring ferroelectric oxide thin film. The second harmonic generation response at the heterointerface is either substantially enhanced or almost entirely quenched by an underlying ferroelectric domain wall depending on its chirality, and can be further tailored by the polar domains. Unlike the extensively studied coupling mechanisms driven by charge, spin, and lattice, the interfacial tailoring effect is solely mediated by the polar symmetry, as well explained via our density functional theory calculations, pointing to a new material strategy for the functional design of nanoscale reconfigurable optical applications.

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Source: https://tomesphere.com/paper/1903.01664