  The AdS/CFT correspondence predicts that background non-abelian magnetic
fields induce instabilities in strongly-coupled systems with non-abelian global
symmetries. These instabilities lead to the formation of vortex lattices in
which the non-abelian currents "antiscreen" the applied magnetic field. From
the bulk perspective, this behaviour can be traced to a well-known instability
of Yang-Mills theory. We analyse the phase structure of the instability and
comment on aspects of the vortex lattice.
