Magnonic band structure of domain wall magnonic crystals

摘要

Magnonic crystals are prototype magnetic metamaterials designed for thecontrol of spin wave propagation. Conventional magnonic crystals are composedof single domain elements. If magnetization textures, such as domain walls,vortices and skyrmions, are included in the building blocks of magnoniccrystals, additional degrees of freedom over the control of the magnonic bandstructure can be achieved. We theoretically investigate the influence of domainwalls on the spin wave propagation and the corresponding magnonic bandstructure. It is found that the rotation of magnetization inside a domain wallintroduces a geometric vector potential for the spin wave excitation. Thecorresponding Berry phase has quantized value $4 n_w \pi$, where $n_w$ is thewinding number of the domain wall. Due to the topological vector potential, themagnonic band structure of magnonic crystals with domain walls as comprisingelements differs significantly from an identical magnonic crystal composed ofonly magnetic domains. This difference can be utilized to realize dynamicreconfiguration of magnonic band structure by a sole nucleation or annihilationof domain walls in magnonic crystals.