Surface Ferron Excitations in Ferroelectrics and Their Directional Routing

TL;DR

This paper predicts surface polarization waves, called ferrons, in ferroelectric insulators, highlighting their unique properties and potential for optical routing due to anisotropic directional emissions.

Contribution

It introduces the concept of ferrons in ferroelectrics, analyzing their properties and differences from magnetic magnons, and explores their potential for optical device applications.

Findings

Ferrons are surface polarization waves with properties distinct from magnetic magnons.

Ferrons exhibit locked circular polarization and momentum at the ionic plasma frequency.

Directional emissions enable optical routing in ferroelectric devices.

Abstract

The duality between the electric and magnetic dipoles inspires recent comparisons between ferronics and magnonics. Here we predict surface polarization waves or ``ferrons" in ferroelectric insulators, taking the long-range dipolar interaction into account. We predict properties that are strikingly different from the magnetic counterpart, \textit{i.e.} the surface ``Damon-Eshbach" magnons in ferromagnets. The dipolar interaction pushes the ferron branch with locked circular polarization and momentum to the ionic plasma frequency. The low-frequency modes are on the other hand in-plane polarized normal to their wave vectors. The strong anisotropy of the lower branch renders directional emissions of electric polarization and chiral near fields when activated by a focused laser beam, allowing optical routing in ferroelectric devices.