  We theoretically study the dynamics of ferrimagnetic skyrmions in
inhomogeneous metallic films close to the angular momentum compensation point.
In particular, it is shown that the line of the vanishing angular momentum can
be utilized as a self-focusing racetrack for skyrmions. To that end, we begin
by deriving the equations of motion for the dynamics of collinear ferrimagnets
in the presence of a charge current. The obtained equations of motion reduce to
those of ferromagnets and antiferromagnets at two special limits. In the
collective coordinate approach, a skyrmion behaves as a massive charged
particle moving in a viscous medium subjected to a magnetic field. Analogous to
the snake orbits of electrons in a nonuniform magnetic field, we show that a
ferrimagnet with the nonuniform angular momentum density can exhibit snake
trajectories of skyrmions, which can be utilized as racetracks for skyrmions.
