  Patterned magnetic nanostructures are potential candidates for future energy
efficient, on-chip communication devices. Here, we have experimentally and
numerically studied the role of nanochannels to manipulate spin waves in
Ni80Fe20 connected nanodot arrays of varying filling fraction. Rich spin-wave
spectra are observed in these samples, where the number of spin-wave modes
decreases with increasing filling fraction due to the retrenchment of the
demagnetizing field. The nanochannels affect the spin-wave modes of the
connected dots through dipole-exchange coupling. For all modes the vertical
nanochannels couple the nanodots, except for the highest frequency modes where
all nanochannels act as coupler. This feature is further explored in the
simulation, which reveals that only the highest frequency mode can propagate
through all the nanochannels, analogues to an electronic demultiplexer. This
study will be useful to understand the role of nanochannels in patterned
magnetic nanostructures and their applications in spin-wave based communication
devices.
