  Recent observations revealed organised structures in protoplanetary disks,
such as axisymmetric rings or horseshoe concen- trations evocative of
large-scale vortices. These structures are often interpreted as the result of
planet-disc interactions. However, these disks are also known to be unstable to
the magneto-rotational instability (MRI) which is believed to be one of the
dominant angular momentum transport mechanism in these objects. It is therefore
natural to ask if the MRI itself could produce these structures without
invoking planets. The nonlinear evolution of the MRI is strongly affected by
the low ionisation fraction in protoplanetary disks. The Hall effect in
particular, which is dominant in dense and weakly ionised parts of these
objects, has been shown to spontaneously drive self- organising flows in
shearing box simulations. Here, we investigate the behaviour of global
MRI-unstable disc models dominated by the Hall effect and characterise their
dynamics. We perform 3D unstratified Hall-MHD simulations of keplerian disks
for a broad range of Hall, ohmic and ambipolar Elsasser numbers. We confirm the
transition from a turbulent to an organised state as the intensity of the Hall
effect is increased. We observe the formation of zonal flows, their number
depending on the available magnetic flux and on the intensity of the Hall
effect. For intermediate Hall intensity, the flow self-organises into
long-lived magnetised vortices. Neither the addition of a toroidal field nor
ohmic or ambipolar diffusion drastically change this picture in the range of
parameters we have explored. The ability of these structures to trap dust
particles in this configuration is demonstrated. We conclude that Hall-MRI
driven organisation is a plausible scenario which could explain some of the
structures found in recent observations.
