Figure 5. Illustration of substrate induced phonon drag effect on the transport of magnons in Bi-YIG.

(a) Illustration of the movement of phonons in the substrate and magnons in the Bi-YIG in transverse geometry. In this geometry, phonons move parallel to magnons and hence can drag them along. (b) Illustration of the movement of phonons in the substrate and magnons in the Bi-YIG in longitudinal geometry. In this case, movement of phonons and magnons take place in series.