  In this work, we consider the physics of the interaction between a planet and
a magnetized gaseous protoplanetary disc. We investigate the migration of a
planet in a disc that is threaded with an azimuthal magnetic field. We find
that, for a larger magnetic field amplitude, there is an increasingly large
positive torque on the planet from the disc, resulting in slowed and even
outward migration. Our results indicate that magnetic resonances due to a
purely azimuthal, ordered magnetic field can slow or stop the inward migration
of Jupiter-mass, Saturn-mass, and $5 M_{\oplus}$ planets.
