  We analytically and numerically investigate magneto-plasmons in metal films
surrounded by a ferromagnetic dielectric. In such waveguide using a metal film
with a thickness exceeding the Skin depth, an external magnetic field in the
transverse direction can induce a significant spatial asymmetry of mode
distribution. Superposition of the odd and the even asymmetric modes over a
distance leads to a concentration of the energy on one interface which is
switched to the other interface by the magnetic field reversal. The requested
magnitude of magnetization is exponentially reduced with the increase of the
metal film thickness. Based on this phenomenon, we propose a
waveguide-integrated magnetically controlled switchable plasmonic routers with
99-%-high contrast within the optical bandwidth of tens of THz. This
configuration can also operate as a magneto-plasmonic modulator.
