Experimental observation of the interaction of propagating spin waves with N\'eel domain walls in a Landau domain structure

The interaction of propagating dipolar spin waves with magnetic domain walls is investigated in square-shaped microstructures patterned from the Heusler compound Co${}_2$Mn${}_{0.6}$Fe${}_{0.4}$Si. Using magnetic force microscopy, the reversible preparation of a Landau state with four magnetic domains separated by N'eel domain walls is confirmed. A local spin-wave excitation using a microstructured antenna is realized in one of the domains. It is shown by Brillouin light scattering microscopy (BLS) that the domain structure in the remanence state has a strong influence on the spin-wave excitation and propagation. The domain walls strongly reflect the spin waves and can be used as spin-wave reflectors. A comparison with micromagnetic simulations shows that the strong reflection is due to the long-range dipolar interaction which has important implications for the use of these spin waves for exerting an all-magnonic spin-transfer torque.