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

TL;DR

This study demonstrates how Nél domain walls in a Landau structure strongly reflect propagating spin waves, with implications for magnonic devices, confirmed through experiments and micromagnetic simulations.

Contribution

It provides experimental evidence of spin wave reflection by Nél domain walls in a Landau state and highlights the role of dipolar interactions in this process.

Findings

Domain walls act as strong spin-wave reflectors

Spin waves are influenced by the magnetic domain structure

Micromagnetic simulations confirm dipolar interaction effects

Abstract

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.