Control of band gap of spin waves in width-modulated nanostrip using voltage-controlled magnetic anisotropy: Spin wave filter

A spin-wave filter that can operate at gigahertz frequencies may be built using a nanostrip magnonic-crystal waveguide with spatially periodic width modulation. Here, micromagnetic simulations are used to demonstrate the unique planar structure of magnonic-crystal waveguide composed of a magnetic material. In this structure, the permitted and forbidden bands of propagating dipole-exchange spin waves may be adjusted by periodic modulation of varying widths in thin-film nanostrips. A periodic nanostrip with a variable width, in contrast to a normal nanostrip with a fixed width, results in the production of forbidden bands (band gaps) as a consequence of spin-wave reflection by the periodic potential spurred on by long-range dipolar interactions. In this work, it is shown that the band structures of a width-modulated magnonic-crystal waveguide can be effectively tuned by controlling the magnetic anisotropy with a voltage. This research may provide a path toward the practical implementation of gigahertz-frequency, broadband spin wave filters.