  We argue that spin and valley-polarized metallic phases recently observed in
graphene bilayers and trilayers support chiral edge modes that allow spin waves
to propagate ballistically along system boundaries without backscattering. The
chiral edge behavior originates from the interplay between the momentum-space
Berry curvature in Dirac bands and the geometric phase of a spin texture in
position space. The edge modes are weakly confined to the edge, featuring
dispersion which is robust and insensitive to the detailed profile of
magnetization at the edge. This unique character of edge modes reduces their
overlap with edge disorder and enhances the mode lifetime. The mode propagation
direction reverses upon reversing valley polarization, an effect that provides
a clear testable signature of geometric interactions in isospin-polarized Dirac
bands.
