Fig. 1: Schematic of the experiment.

a cross-section of the nonlocal device. A current I flowing in a Pt wire (injector) induces a spin accumulation via the spin Hall effect at the interface with YIG, which leads to the nonequilibrium injection of magnons in YIG. This magnon accumulation (carrying a spin angular momentum represented by the direction of the wavy arrow) can either be detected electrically by a second Pt electrode (detector) or optically via BLS. b, c Magnons can be created or annihilated, respectively, by the electronic spin accumulation at the interface via exchange coupling between the Pt and Fe atoms in the YIG layer. d Optical micrograph of the investigated device with contact scheme and coordinate system. The magenta cross marks the position of the laser spot used for the BLS measurements.