Geometric magnonics with chiral magnetic domain walls

Abstract

Spin wave, the collective excitation of magnetic order, is one of the fundamental angular momentum carriers in magnetic systems. Understanding the spin wave propagation in magnetic textures lies in the heart of developing pure magnetic information processing schemes. Here we show that the spin wave propagation across a chiral domain wall follows simple geometric trajectories, similar to the geometric optics. And the geometric behaviors are qualitatively different in normally magnetized film and tangentially magnetized film. We identify the lateral shift, refraction, and total reflection of spin wave across a ferromagnetic domain wall. Moreover, these geometric scattering phenomena become polarization-dependent in antiferromagnets, indicating the emergence of spin wave birefringence inside antiferromagnetic domain wall.

Magnetically switchable spin wave retarder with $90^\circ$ antiferromagnetic domain wall

“…With fully unlocked polarization for spin wave in antiferromagnets [20][21][22][23] , the interplay features are remarkably enriched. The antiferromagnetic skyrmion is shown to induce polarization-dependent magnon Hall effect 24,25 , and a uniaxial 180 • antiferromagnetic domain wall with Dzyaloshinskii-Moriya interaction (DMI) can induce spin wave polarizing and retarding 26 , as well as double refraction 27 . Reversely, the motion of domain wall in antiferromagnets can be also controlled via simply tuning the spin wave polarization [28][29][30] .…”