Ultrabroadband spin-wave propagation in Co-2(Mn0.6Fe0.4)Si thin films

Ferromagnetic Heusler alloys with low magnetic damping are highly promising materials for magnonic devices, which rely on the excitation and detection of spin waves. Using all-electrical spin-wave spectroscopy we report spin-wave propagation in sputtered Co-2(Mn0.6Fe0.4) Si Heusler alloy thin films with a thickness of 50 nm. We integrated a nanostructured microwave antenna to locally excite and detect propagating spin waves in a Damon-Eshbach configuration. We estimate the group velocity to be up to 12.0 km/s and we observe spin-wave propagation with a frequency band as broad as 15 GHz. From the experimental frequency dependence of group velocity we calculate the spin-wave dispersion. Our results show that all-electrical measurements are a powerful method for determining the fundamental spin-wave characteristics of Heusler alloys, over a broad and tunable range of frequencies, and with group velocities an order of magnitude higher than in conventional materials.