Dyonic Stars for Holography

We construct back-reacted asymptotically AdS_4 backgrounds with both electric and magnetic charge, at finite temperature and chemical potential. The system consists of a condensed bulk Dirac field hovering over a charged black brane. We give a detailed microscopic treatment of the bulk fermions, from which we derive the usual fluid approximations describing the condensate. In the context of holography, such a gravitational solution is dual to a (2+1)-dimensional CFT with a U(1) current, at finite density and strong coupling, subjected to a transverse magnetic field.