We suggest to use spatially-modulated strain for control of a spin-wave propagating inside a bulk magnet. The modulation with the wave vector q=2k 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 the one for a tunneling particle in a symmetric double-well potential.
Here, a moving spin-wave being subjected to the 2k-lattice modulation after some time will alter its propagation direction to the opposite one, and so on. The alternating motion of the spin-wave, which can be controlled by the amplitude of the strain, carries information about the exchange coupling constants of the magnet and their sensitivity to the lattice deformation. The effect can be utilized for spectroscopy as well as control of the spin-wave propagation that can be useful for magnonic applications. The control may include the delay line and filtering of the spin waves.
