Optical and extreme UV studies of spin dynamics in metallic and insulating ferrimagnets

We present all-optical studies of spin dynamics in two classes ferrimagnets. Both sets experiments use table-top laser-based pump–probe techniques to examine the ultrafast and longer timescale excitations. visible/near infra-red time-resolved magneto-optical Kerr effect (tr-MOKE) follow a series metallic (FeCo)1−xGdx thin films with varying Gd content. Magnetic compensation occurs at concentration ≈26%, exhibit non-monotonic variation effective magnetization. also an insulating NiFe2O4 spinel using up extreme ultraviolet energies, which permit element-specific investigations. The element delay scans reveal non-trivial interaction between excitations on different magnetic sub-lattices insulator.