Electronic Supplementary Information contains the following files:

RotMeanRadialArealDensity.pdf : Radial surface densities of the dried agglomerates normalized by the number of particles (so that the integral of the curve is equal to one), obtained with rotating magnetic fields of various intensities. The density of particles is mainly uniform all over the drop, but a slight coffee-ring effect is observed as a local maximum near the edge. However, the amplitude of this peak decreases when the amplitude of the external magnetic field increases.

OscMeanRadialArealDensity.pdf : Radial surface densities of the dried agglomerates normalized by the number of particles (so that the integral of the curve is equal to one), obtained with oscillating magnetic fields of various intensities. The density of particles is mainly uniform all over the drop, but a slight coffee-ring effect is observed as a local maximum near the edge. However, the amplitude of this peak decreases when the amplitude of the external magnetic field increases.

2uLAllDrop0GSpeed10XComp.avi : 10X accelerated video of an evaporating droplet without magnetic field. One can see that the particles do not agglomerate during the first stages of evaporation.

2uLAllDrop18GSpeed10XComp.avi : 10X accelerated video of an evaporating droplet with a constant and homogeneous magnetic field of 18 G. One can see that the particles agglomerate into chains from the beginning of the evaporation, then enhancing the sedimentation of the particles.

2uLAllDrop18GSpeed10XLowPBSComp.avi : 10X accelerated video of an evaporating droplet with a constant and homogeneous magnetic field of 18 G, containing a volume fraction of PBS of 6.10^{-3} (other data were obtained with volume fraction of PBS of 50.10^{-3}). As can be seen on this video, strong outward flows at the end of the evaporation destroys the agglomerated chains and the eventual dried deposits presents a strong coffee-ring.