Pure spin currents - the flow of angular momentum without accompanying a charge flow - play an essential role for the low energy cost, high efficiency spintronics. Discoveries of pure spin current generation, transport and interaction with magnetic subsystems enable exciting new prospects both for fundamental physics and technological applications, such as spin Hall effect, spin pumping, topological insulators, quantum materials, spin caloritronics, and the well-established current-induced-magnetization dynamics.
The talk will focus on: i) pure spin current generation via spin pumping, an emerging method to dynamically inject pure spin currents into non-magnetic materials. Spin pumping is robust to provide high magnitude spin currents and flexible in material selection. In addition, owing to the low energy cost to excite, spin pumping intrinsically provides a clean platform with low heat background and sufficient spin injection for fundamental spin-physics studies. I will present my experimental studies on spin pumping in metal, semiconductor and insulator systems and related fundamental physics; ii) pure spin current generation by non-magnetic materials with strong spin-orbit coupling, e.g. spin Hall effect etc., and spin torque ferromagnetic resonance (ST-FMR), a new technique that is suitable to study such class of effects. Measurement of spin Hall angles, manipulation of magnetic damping, current-induced magnetization self-oscillation and microwave emission will be presented.