Ramsauer-Townsend Resonance for Spin Waves

Spin waves are fluctuations about the stable configuration in a ferromagnet. As spin waves are free from Joule heating, they are interesting for technological applications. Controlling spin waves propagating in solids relies on the predefined, constant magnetic parameters. However, recently, it has been shown that it is possible to have a dynamic variation of these parameters. Using a laser, thermal landscapes are created in the magnetic medium that results in a modulation of the saturation magnetization[1].

We excite spin waves on a thin ferromagnetic film using micromagnetic simulations. The film has a region where saturation magnetization is decreased, creating a potential well. We calculate the spin wave reflection coefficient for different widths of the well. We found that there are resonances on the reflection coefficient. These resonances resemble the ones found in the quantum mechanical Ramsauer-Townsend (RT) effect.[2] The RT effect describes an electron wave propagating above a finite potential well and exhibits resonances for certain energies and well widths.

Our results may be of interest for magnonic applications by only varying the width of the well.

[1] Chumak, A. V., et al. Nat. Phys. 11, 453–461 (2015)
[2]Bailey, V. A. et al. Philosophical Magazine, S.6, 42 (1921)