  We demonstrate both analytically and numerically the existence of optical
pulling forces acting on particles located near plasmonic interfaces. Two main
factors contribute to the appearance of this negative reaction force. The
interference between the incident and reflected waves induces a rotating dipole
with an asymmetric scattering pattern while the directional excitation of
surface plasmon polaritons (SPP) enhances the linear momentum of scattered
light. The strongly asymmetric SPP excitation is determined by spin-orbit
coupling of the rotating dipole and surface plasmon polariton. As a result of
the total momentum conservation, the force acting on the particle points in a
direction opposite to the incident wave propagation. We derive analytical
expressions for the force acting on a dipolar particles placed in the proximity
of plasmonic surfaces. Analytical expressions for this pulling force are
derived within the dipole approximation and are in excellent agreement with
results of electromagnetic numerical calculations. The forces acting on larger
particles are analyzed numerically, beyond the dipole approximation.
