Controlling terahertz sound propagation: some preliminary Inelastic X-Ray Scattering result

The control of sound propagation in materials via the design of their elastic properties is an exciting task at the forefront of Condensed Matter. It becomes especially compelling at terahertz frequencies, where phonons are the primary conveyors of heat flow. Despite the increasing focus on this goal, this field of research is still in its infancy. To achieve a few advances in this field, we performed several Inelastic X-Ray Scattering (IXS) measurements on elementary systems as dilute suspensions of nanoparticles (NPs) in liquids. We found that nanoparticles can effectively impact the sound propagation of the hosting liquid. We also explored the possibility of shaping terahertz sound propagation in a liquid upon confinement on quasi-unidimensional cavities. These results are here reviewed and discussed, and future research directions are finally outlined.