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The emerging field of magnonics uses spin waves and their quanta, magnons, to implement wave-based computing on the micro- and nanoscale. Multifrequency magnon networks would allow for parallel data processing within single logic elements, whereas this is not the case with conventional transistor-based electronic logic. However, a lack of experimentally proven solutions to efficiently combine and separate magnons of different frequencies has impeded the intensive use of this concept. Herein, the experimental realization of a spin-wave demultiplexer enabling frequency-dependent separation of magnonic signals in the gigahertz range is demonstrated. The device is based on 2D magnon trans- port in the form of spin-wave beams in unpatterned magnetic films. The intrinsic frequency dependence of the beam direction is exploited to realize a passive functioning obviating an external control and additional power consumption. This approach paves the way to magnonic multiplexing circuits enabling simultaneous information transport and processing.
Herein, experimental demonstration of the parallel parametric generation of spin waves in a microscaled yttrium iron garnet waveguide with nanoscale thickness is presented. Using Brillouin light scattering microscopy, the parametric excitation of the first and second waveguide modes by a stripline microwave pumping source is observed. Micromagnetic simulations reveal the wave vector of the parametrically generated spin waves. Based on analytical calculations, which are in excellent agreement with experiments and simulations, it is proved that the spin-wave radiation losses are the determinative term of the parametric instability threshold in this miniaturized system. The used method enables the direct excitation and amplification of nanometer spin waves dominated by exchange interactions. The presented results pave the way for integrated magnonics based on insulating nanomagnets.
Magnonics attracts increasing attention in the view of low-energy computation technologies based on spin waves. Recently, spin-wave propagation in longitudinally magnetized nano-scaled spin-wave conduits was demonstrated, proving the fundamental feasibility of magnonics at the sub-100 nm scale. Transversely magnetized nano-conduits, which are of great interest in this regard as they offer a large group velocity and a potentially chirality-based protected transport of energy, have not yet been investigated due to their complex internal magnetic field distribution. Here, we present a study of propagating spin waves in a transversely magnetized nanoscopic yttrium iron garnet conduit of 50 nm width. Space and time-resolved microfocused Brillouin-light-scattering spectroscopy is employed to measure the spin-wave group velocity and decay length. A long-range spin-wave propagation is observed with a decay length of up to (8.0 ± 1.5) μm and a large spin-wave lifetime of up to (44.7 ± 9.1) ns. The results are supported with micromagnetic simulations, revealing a broad single-mode frequency range and the absence of a mode localized to the edges. Furthermore, a frequency nonreciprocity for counter-propagating spin waves is observed in the simulations and the experiment, caused by the trapezoidal cross section of the structure. The revealed long-distance spin-wave propagation on the nano-scale is particularly interesting for an application in spin-wave devices, allowing for long-distance transport of information in magnonic circuits and low-energy device architectures.