Advances in Brillouin–Mandelstam light-scattering spectroscopy

Recent years have witnessed a much broader use of Brillouin inelastic light-scattering spectroscopy for the investigation of phonons and magnons in novel materials, nanostructures and devices. Driven by the developments in instrumentation and the strong need for accurate knowledge on the energies of elemental excitations, Brillouin–Mandelstam spectroscopy is rapidly becoming an essential technique that is complementary to Raman inelastic light-scattering spectroscopy. We provide an overview of recent progress in the Brillouin light-scattering technique, focusing on the use of this photonic method for the investigation of confined acoustic phonons, phononic metamaterials and magnon propagation and scattering. This Review emphasizes the emerging applications of Brillouin–Mandelstam spectroscopy for phonon-engineered structures and spintronic devices, and concludes with a perspective on future directions.