2D Phononic Crystals: Progress and Prospects in Hypersound and Thermal Transport Engineering

• Published in: Advanced functional materials Vol. 30; no. 8
• Main Authors: Sledzinska, Marianna, Graczykowski, Bartlomiej, Maire, Jeremie, Chavez‐Angel, Emigdio, Sotomayor‐Torres, Clivia M., Alzina, Francesc
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.02.2020
• Subjects: 2D phononic crystals; Elastic properties; Elastic waves; Group velocity; Heat transmission; hypersound; Materials science; Nanofabrication; nanoscale thermal transport; phononics; Phonons; State variable; Thermal management; Wave propagation
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201904434

The central concept in phononics is the tuning of the phonon dispersion relation, or phonon engineering, which provides a means of controlling related properties such as group velocity or phonon interactions and, therefore, phonon propagation, in a wide range of frequencies depending on the geometries and sizes of the materials. Phononics exploits the present state of the art in nanofabrication to tailor dispersion relations in the range of GHz for the control of elastic waves/phonons propagation with applications toward new information technology concepts with phonons as state variable. Moreover, phonons provide an adaptable approach for supporting a coherent coupling between different state variables, and the development of nanoscale optomechanical systems during the last decade attests this prospect. The most extended approach to manipulate the phonon dispersion relation is introducing an artificial periodic modulation of the elastic properties, which is referred to as phononic crystal (PnC). Herein, the focus is on the recent experimental achievements in the fabrication and application of 2D PnCs enabling the modification of the dispersion relation of surface and membrane modes, and presenting phononic bandgaps, waveguiding, and confinement in the hypersonic regime. Furthermore, these artificial materials offer the potential of modifying and controlling the heat flow to enable new schemes in thermal management. 2D phononic crystals display modified dispersion relation of phonons in a frequency range well within the gigahertz with the present nanofabrication techniques. Coherent interaction with photons and possible wave‐like effects impacting the thermal transport in such systems open further prospects of phonons being key actors in signal and information processing schemes.