  We study the motion of a charged particle with magnetic moment in external
electromagnetic fields utilizing covariant unification of Gilbertian and
Amperian descriptions of particle magnetic dipole moment. Considering the case
of a current loop, our approach is verified by comparing classical dynamics
with the classical limit of relativistic quantum dynamics. We obtain motion of
a charged particle in the presence of an external linearly polarized EM (laser)
plane wave field incorporating the effect of spin dynamics. For specific
laser-particle initial configurations, we determine that the Stern-Gerlach
force can have a cumulative effect on the trajectory of charged particles.
