In this paper, we consider a new mechanism for stopping the inward migration of a low-mass planet embedded in a gaseous protoplanetary disc. It operates when a low-mass planet (for example a super-Earth) encounters outgoing density waves excited by another source in the disc. This source could be a gas giant in an orbit interior to that of the low-mass planet. As the super-Earth passes through the wave field, angular momentum is transferred to the disc material and then communicated to the planet through co-orbital dynamics, with the consequence that its inward migration can be halted or even reversed.
We illustrate how the mechanism we consider works in a variety of different physical conditions employing global two-dimensional hydrodynamical calculations. We confirm our results by performing local shearing box simulations in which the super-Earth interacts with density waves excited by an independent harmonically varying potential. Finally, we discuss the constraints arising from the process considered here, on formation scenarios for systems containing a giant planet and lower mass planet in an outer orbit with a 2:1 commensurability such as GJ 876.