Spin wave propagation in corrugated waveguides

Curvature-induced effects allow us to tailor the static and dynamic response of a magnetic system with a high degree of freedom. We study corrugated magnonic waveguides deposited on a sinusoidally modulated substrate prepared by focused electron beam-induced deposition. The curvature of the waveguides with thicknesses comparable to the amplitude of modulation modifies the contributions of dipolar and exchange energies and results in an effective anisotropy term, which is strong enough to overcome the shape anisotropy. At zero external magnetic field, the magnetization of the waveguide then points perpendicular to its long axis in a geometry, which is best-suited to spin-wave propagation. We show, by Brillouin light scattering microscopy, that without the presence of the external magnetic field, spin waves propagate over a distance 10×larger in the corrugated waveguide than in the planar waveguide. We further analyze the influence of the modulation amplitude on the spin-wave propagation length and conclude that for moderate modulation amplitudes, the spin-wave decay length is not affected. For larger amplitudes, the decay length decreases linearly with increasing modulation. The presented approach opens many possibilities for the design of complex 2D magnonic circuits where the waveguides can be oriented in any direction and placed anywhere on the sample while still allowing spin-wave propagation with the same efficiency.