Ultrafast Optomagnonics in Ferrimagnetic Multi-Sublattice Garnets

This review discusses the ultrafast magnetization dynamics within the gigahertz to terahertz frequency range in ferrimagnetic rare-earth iron garnets with different substitutions. In these garnets, the roles of spin-orbit and exchange interactions have been detected using femtosecond laser pulses via the inverse Faraday effect. The all-optical control of spin-wave and Kaplan-Kittel exchange resonance modes in different frequency ranges is shown. Generation and localization of the electric field distribution inside the garnet through the metal-bound surface plasmon-polariton strongly enhance the amplitude of the exchange resonance modes. The exchange resonance mode in yttrium iron garnets was observed using circularly polarized Raman spectroscopy. The results of this study may be utilized in the development of a wide class of optomagnonic devices in the gigahertz to terahertz frequency range.