  We show that ac driven skyrmion lattices in a weak pinning channel confined
by regions of strong pinning exhibit edge transport carried by skipping orbits
while skyrmions in the bulk of the channel undergo localized orbits with no net
transport. The magnitude of the edge currents can be controlled by varying the
amplitude and frequency of the ac drive or by changing the ratio of the Magnus
force to the damping term. We identify a localized phase in which the orbits
are small and edge transport is absent, an edge transport regime, and a
fluctuating regime that appears when the ac drive is strong enough to
dynamically disorder the skyrmion lattice. We also find that in some cases,
multiple rows of skyrmions participate in the transport due to a drag effect
from the skyrmion-skyrmion interactions. The edge currents are robust for
finite disorder and should be a general feature of skyrmions interacting with
confined geometries or inhomogeneous disorder under an ac drive. We show that
similar effects can occur for skyrmion lattices at interfaces or along domain
boundaries for multiple coexisting skyrmion species. The edge current effect
provides a new method to control skyrmion motion, and we discuss the connection
of these results with recent studies on the emergence of edge currents in
chiral active matter systems and gyroscopic metamaterials.
