  The emerging field of magnonics employs spin waves and their quanta, magnons,
to implement wave-based computing on the micro- and nanoscale. Multi-frequency
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. In this Letter, the experimental realization
of a spin-wave demultiplexer enabling frequency-dependent separation of
magnonic signals in the GHz range is demonstrated. The device is based on
two-dimensional magnon transport 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.
