  Coupling between spin waves (SWs) and other types of waves in nanostructured
magnetic media has garnered increased attention in recent years because of the
rich physics and the potential to produce disruptive technologies. Among this
family of intriguing phenomena, we recently reported a new one: coupling
between SWs and hybridized phonon-plasmon waves, resulting in tripartite
coupling of magnons, phonons, and plasmons. Here, this acousto-plasmo-magnonic
phenomenon is studied in a two-dimensional periodic array of bilayered [Co/Al]
nanodots on a silicon substrate, where the Co is a magnetostrictive constituent
responsive to magneto-elastic coupling and the Al acts as a source of surface
plasmons. Time-resolved magneto-optical-Kerr-effect microscopy revealed
parametric amplification and strong coupling between two spin wave modes
mediated by a hybrid phonon-plasmon wave. The strong coupling forms a new
quasi-particle: the phonon-plasmonmagnon polariton.
