Spin Waves on Spin Structures: Topology, Localization, and Nonreciprocity
This chapter discusses the propagation of spin waves along domain walls and consequences of the Dzyaloshinskii-Moriya interaction (DMI) on their dispersion. It also discusses how DMI affects the gap between energies of freely propagating spin waves and spin waves channeled along walls, as well as consequent nonreciprocities. The chapter describes a possibility for creating a mesoscopic metamaterial analogue of domain wall channeling. It also describes aspects of ongoing work aimed at using magnetic configurations in spin ice to manipulate microwave resonances. The chapter discusses few specific consequences of the interaction, namely the appearance of an underlying drift current in certain geometries and focusing effects such as caustics. It examines exclusively square artificial spin ice (ASI) for which magnetic elements are aligned in few sets of rows on square lattice. The chapter describes a number of recent examples of how relatively simple material designs can produce spin wave phenomena, such as channeled nonreciprocity, that is at once interesting and potentially useful.