Magnon Spin Hall Effect

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The realization of insulator-based spintronics, operating with pure spin currents perfectly decoupled from electron currents, potentially provides the basis for a move away from conventional dissipation- limited electronics to a fundamentally different signal-transfer paradigm. In magnetic insulators (or ferrites) spin angular momentum can be transferred by magnons, the quanta of spin waves over millimetre distances. Spin pumping phenomena (which provide a bridge between spin waves and conventional spin currents) together with the spin Hall effect (which provides a bridge between conventional spin currents and electron currents) are of paramount importance for the further development of this field. Our study will focus on the mechanisms of generation, detection, and amplification of spin waves or magnons by electron currents using both the direct and inverse spin Hall effects. Time-, space- and wavevector-resolved Brillouin light scattering spectroscopy as well as microwave techniques will be used to study these effects in detail. The investigation of the influence of spin-wave frequency, wavevector, group velocity and phase coherency on the spin pumping efficiency will provide new understanding of spin pumping in magnetic insulator/ nonmagnetic metal systems. A particular focus will lie on the amplification of spin waves using the spin Hall effect. In addition, the work will establish milestones in the development of magnonbased spintronics and its integration with conventional electronics.