Fig. 2: Experimental setup and time-resolved magneto-optical images of the reflection dynamics.

a A schematic of the experimental setup for the time-resolved magneto-optical microscopy. A pulse laser light is divided into pump and probe beams which enter into the sample at different time delay. The pump beam excites spin waves, and the probe beam is detected with a charge-coupled device (CCD) camera. The inset shows a magnified view of the sample configuration. A spin wave is excited by a pump beam focused on the sample. The focus is shaped into an ellipse to determine the propagation direction of the spin wave. The excited spin wave is reflected at the sample edge. b–d Reflection dynamics of spin waves obtained from the out-of-plane magnetized film at the time delay of 12 ns (b), 18 ns (c), and 24 ns (d). The excited spin wave reflects at the sample edge and splits into two waves with different wavevectors k₁ and k₂.