  The recently introduced concept of "surface Berry plasmons" is studied in the
concrete instance of a ferromagnetic conductor in which the Berry curvature,
generated by spin-orbit (SO) interaction, has opposite signs for carriers
parallel or antiparallel to the magnetization. By using collisionless hy-
drodynamic equations with appropriate boundary conditions, we study both the
surface plasmons of a three-dimensional ferromagnetic conductor and the edge
plasmons of a two-dimensional one. The anomalous velocity and the broken
inversion symmetry at the surface or the edge of the conductor create a
"handedness", whereby the plasmon frequency depends not only on the angle
between the wave vector and the magnetization, but also on the direction of
propagation along a given line. In particular, we find that the frequency of
the edge plasmon depends on the direction of propagation along the edge. These
Berry curvature effects are compared and contrasted with similar effects
induced in the plasmon dispersion by an external magnetic field in the absence
of Berry curvature. We argue that Berry curvature effects may be used to
control the direction of propagation of the surface plasmons via coupling with
the magnetization of ferromagnetic conductors, and thus create a link between
plasmonics and spintronics.
