  Highly spatially-squeezed polaritons, with propagation momentum significantly
larger than free-space modes at the same frequency, enable varied and extreme
control over light-matter interaction. Compared to other polaritons, surface
magnon polaritons, the magnetic counterpart of surface phonon polaritons, have
received relatively little attention. Here, we investigate the dispersion and
properties of surface-magnon polaritons, highlighting the impact of geometric
similarities and applying them to various surface-magnon polariton devices in
both conventional and topological settings. Our theory predicts a method for
strongly localizing and significantly enhancing magnetic fields in the
microwave range and developing compact and lossless connectors capable of
interconnecting waveguides with vastly different input and output impedances.
Our work opens new avenues for manipulating magnetic fields in the microwave
regime and for exploring topological phases in polariton platforms.
