  We present a physically motivated model for the manner in which a stellar
magnetic field sculpts the inner edge of a protoplanetary disk, and examine the
consequence for the migration and stopping of sub-Neptune and super-Earth
planets. This model incorporates a transition zone exterior to the inner
truncation of the disk, where the surface density profile is modified by the
diffusion of the stellar magnetic field into the disk. This modification
results in a migration trap at the outer edge of the transition zone. We
performed simulations of single planet migration, considering a range of
stellar magnetic field strengths and magnetic diffusion profiles. Our
simulations show a tight relationship between the final locations of planets
and the total magnetic budget available for the disk from their host star. We
found that a stellar magnetic field between 67 to 180G and a power-law index
between 3 and 2.75 can reasonably reproduce the location at which the observed
occurrence rate of close-in Super-Earth and Sub-Neptune populations changes
slope.
