Temporal Evolution of Auto-Oscillations in an Yttrium-Iron-Garnet/Platinum Microdisk Driven by Pulsed Spin Hall Effect-Induced Spin-Transfer Torque

The temporal evolution of pulsed spin Hall effect-spin transfer torque (SHE-STT) driven auto-oscillations in a yttrium iron garnet (YIG)-platinum (Pt) microdisk is studied experimentally using time-resolved Brillouin light scattering spectroscopy. The frequency of the auto-oscillations is different in the center when compared to the edge of the disk and is related to the simultaneous STT excitation of a bullet and a non-localized spin-wave mode. Furthermore, the magnetization precession intensity saturates on a time scale of 20 ns or longer, depending on the current density. For this reason, our findings suggest that a proper ratio between the current and the pulse duration is of crucial importance for future STT-based devices.