Acoustic Localization Phenomena in Ferroelectric Nanophononic Devices

TL;DR

This paper experimentally investigates phononic resonances in ferroelectric nanostructures, demonstrating acoustic wave confinement, coupling effects, and Bloch-like oscillations in nanocavities, advancing the understanding of nanoscale wave localization.

Contribution

It presents the first experimental demonstration of acoustic phenomena such as confinement, coupling, and Bloch oscillations in ferroelectric nanophononic devices.

Findings

Confinement of acoustic waves at 100 GHz in nanocavities

Observation of acoustic molecule formation through hybrid nanocavities

Detection of Bloch-like oscillations in coupled resonator systems

Abstract

The engineering of phononic resonances in ferroelectric structures appears as a new knob in the design and realization of novel multifunctional devices. In this work we experimentally study phononic resonators based on insulating (BaTiO3, SrTiO3) and metallic (SrRuO3) oxides. We experimentally demonstrate the confinement of acoustic waves in the 100 GHz frequency range in a phonon nanocavity, the time and spatial beatings resulting from the coupling of two different hybrid nanocavities forming an acoustic molecule, and the direct measurement of Bloch-like oscillations of acoustic phonons in a system formed by 10 coupled resonators. By means of coherent phonon generation techniques we study the phonon dynamics directly in the time-domain. The metallic SrRuO3 introduces a local phonon generator and transducer that allows for the spatial, spectral and time-domain monitoring of the complex generated waves. Our results introduce ferroelectric cavity systems as a new tool for the study of complex wave localization phenomena at the nanoscale.