  We investigate the sedimentation of initially packed paramagnetic particles
in presence of a homogeneous external magnetic field, in a Hele-Shaw cell
filled with water. Although the magnetic susceptibility of the particles is
small and the particle-particle induced magnetic interactions are significantly
smaller compared to the gravitational acceleration, we do observe a measurable
reduction of the decompaction rate as the amplitude of the applied magnetic
field is increased. While induced magnetic dipole-dipole interactions between
particles can be either attracting or repulsive depending on the particles
relative alignment, our observations reveal an effective overall enhancement of
the cohesion of the initial pack of particles due to the induced interactions,
very likely promoting internal chain forces in the initial pack of particles.
The influence of the magnetic field on the particles once they disperse after
being decompacted is on the other hand found to remain marginal.
