Phase stability of magnonic logic operation in the microfabricated ferromagnetic stripe

Magnons, which are the quasi-particles of spin waves, have a great potential to realization of low-energy-dissipation devices, because the magnons deliver an angular momentum and the propagation of magnons is free from Joule heating. Magnons are expected as non-charged new information carriers[1], and logic operation of magnons is demonstrated in ferromagnetic thin film[2]. In order to apply to actual devices, miniaturization of logic circuits is essential for integration of circuits. However, in the micrometer-sized magnon waveguides a confinement of magnon emerges[3] and make magnon propagation complex.
In order to make clear the logic operation of magnon in the micro waveguides, we measured magnon densities of spin-wave interference in 2.5-µm-wide ferromagnetic stripe using microfocused Brillouin light scattering spectroscopy. Spatial mapping of the magnon density revealed that the interference pattern of spin wave is confined within a limited area because of contributions of transverse quantized modes. In the limited area the phase of interference pattern is able to be controlled by the spin-wave phase. A micromagnetic simulation revealed transverse 100 nm interference patterns, which affect a signal-to-noise ratio of logic operation. These results will be important to decide the design of integrated magnonic devices.

References
[1] A. V. Chumak et al., Nat. Commun. 5, 4700 (2014).
[2] N. Sato et al., Appl. Phys. Express 6, 063001 (2013).
[3] P. Pirro et al., Phys. Status Solidi B 248, 1404 (2011).