Highly confined phonon polaritons in monolayers of oxide perovskites

TL;DR

This paper investigates the properties of phonon polaritons in monolayer oxide perovskites, revealing their potential for highly confined light-matter interactions in the terahertz range, comparable to established 2D materials.

Contribution

It provides a first-principles evaluation of phonon polaritons in 2D oxide perovskites, highlighting their promising confinement and propagation qualities for polaritonic applications.

Findings

Phonon polaritons in 2D oxide perovskites are highly confined and comparable to hexagonal boron nitride.

Monolayer oxide perovskites exhibit suitable propagation quality and deceleration factors.

These materials are promising for terahertz polaritonic devices and controlling complex phases of matter.

Abstract

Two-dimensional (2D) materials are able to strongly confine light hybridized with collective excitations of atoms, enabling electric-field enhancements and novel spectroscopic applications. Recently, freestanding monolayers of oxide perovskites have been synthesized, which possess highly infrared-active phonon modes and a complex interplay of competing interactions. In this study, we evaluate central figures of merit for phonon polaritons in the tetragonal phases of the 2D perovskites SrTiO$_3$, KTaO$_3$, and LiNbO$_3$, using density functional theory calculations. Specifically, we compute the 2D phonon-polariton dispersions, the propagation-quality, confinement, and deceleration factors, and we show that they are comparable to those found in the prototypical 2D dielectric hexagonal boron nitride. Our results suggest that monolayers of oxide perovskites are promising candidates for polaritonic platforms in the terahertz spectral range that enable possibilites to control complex phases of matter through strongly enhanced electromagnetic fields.