Control of spin waves by spatially modulated strain

TL;DR

This paper proposes using spatially modulated strain in magnetic materials to control spin wave propagation, enabling potential applications in spintronics and magnonics such as filtering, delay lines, and waveguides.

Contribution

It introduces a novel method of controlling spin waves via magnetoelastic coupling with spatially modulated strain, demonstrating effects analogous to quantum tunneling.

Findings

Modulation with wave vector 2k mixes spin waves near k and -k.

Lifts degeneracy of symmetric and antisymmetric states.

Enables control of spin wave direction and propagation.

Abstract

We suggest using spatially modulated strain for control of a spin wave propagating inside a bulk magnet. The modulation with the wave vector $q=2k$, by virtue of magnetoelasticity, mixes spin waves with wave vectors near $k$ and $-k$. This leads to lifting the degeneracy of the symmetric and antisymmetric eigenstate combinations of these waves. The resulting picture reminds one of a tunneling particle in a symmetric double-well potential. Here, a moving spin wave being subjected to the $2k$-lattice modulation after some time alters its propagation direction to the opposite one, and so on. The effect can be utilized for the control of the spin-wave propagation that can be useful for spintronic and magnonic applications. The control may include a delay line element, filtering, and waveguide of the spin waves.