  Recent observations suggest late accretion, which is generally
nonaxisymmetric, onto protoplanetary disks. We investigated nonaxisymmetric
late accretion considering the effects of magnetic fields. Our model assumes a
cloudlet encounter event at a few hundred au scale, where a magnetized gas
clump (cloudlet) encounters a protoplanetary disk. We studied how the cloudlet
size and the magnetic field strength affect the rotational velocity profile in
the disk after the cloudlet encounter. The results show that a magnetic field
can either decelerate or accelerate the rotational motion of the cloudlet
material, primarily depending on the relative size of the cloudlet to the disk
thickness. When the cloudlet size is comparable to or smaller than the disk
thickness, magnetic fields only decelerate the rotation of the colliding
cloudlet material. However, if the cloudlet size is larger than the disk
thickness, the colliding cloudlet material can be super-Keplerian as a result
of magnetic acceleration. We found that the vertical velocity shear of the
cloudlet produces a magnetic tension force that increases the rotational
velocity. The acceleration mechanism operates when the initial plasma $\beta$
is $ \beta \lesssim 2\times 10^1 $. Our study shows that magnetic fields modify
the properties of spirals formed by tidal effects. These findings may be
important for interpreting observations of late accretion.
