  Various latest experiments have proven the theoretical prediction that domain
walls in planar magnetic structures can channel spin waves as outstanding
magnonic waveguides, establishing a superb platform for building magnonic
devices. Recently, three-dimensional nanomagnetism has been boosted up and
become a significant branch of magnetism, because three-dimensional magnetic
structures expose a lot of emerging physics hidden behind planar ones and will
inevitably provide broader room for device engineering. Skyrmions and
antiSkyrmions, as natural three-dimensional magnetic configurations, are not
considered yet in the context of spin-wave channeling and steering. Here, we
show that skyrmion tubes can act as nonplanar magnonic waveguides if excited
suitably. An isolated skyrmion tube in a magnetic nanoprism induces spatially
separate internal and edge channels of spin waves; the internal channel has a
narrower energy gap, compared to the edge channel, and accordingly can transmit
signals at lower frequencies. Additionally, we verify that those spin-wave
beams along magnetic nanoprism are restricted to the regions of potential
wells. Transmission of spin-wave signals in such waveguides results from the
coherent propagation of locally driven eigenmodes of skyrmions, i.e., the
breathing and rotational modes. Finally, we find that spin waves along the
internal channels are less susceptible to magnetic field than those along the
edge channels. Our work will open a new arena for spin-wave manipulation and
help bridge skyrmionics and magnonics.
