Parametric generation of spin waves in nanoscaled magnonic conduits

The research field of magnonics proposes a low-energy wave-logic computation technology based on spin waves to complement the established complementary metal-oxide-semiconductor technology and provide a basis for emerging unconventional computation architectures. However, magnetic damping is a limiting factor for all-magnonic logic circuits and multidevice networks, ultimately rendering mechanisms to efficiently manipulate and amplify spin waves a necessity. In this regard, parallel pumping is a versatile tool since it allows one to selectively generate and amplify spin waves. While extensively studied in microscopic systems, nanoscaled systems are lacking investigation to assess the feasibility and potential future use of parallel pumping in magnonics. Here, we investigate a longitudinally magnetized 100-nm-wide magnonic nanoconduit using space- and time-resolved microfocused Brillouin-light-scattering spectroscopy. Employing parallel pumping to generate spin waves, we observe that the nonresonant excitation of dipolar spin waves is favored over the resonant excitation of short wavelength exchange spin waves. In addition, we utilize this technique to access the effective spin-wave relaxation time of an individual nanoconduit, observing a large relaxation time up to 115.0±(76)⁢ns. Despite the significant decrease of the pumping efficiency in the investigated nanoconduit, a reasonably small threshold is found rendering parallel pumping feasible on the nanoscale.