Magnetic-field-driven instability in stratified ferrofluids.

We describe a convective instability of a stratified ferrofluid subject to a magnetic field. The ferrofluid is described as binary mixture featuring two important dimensionless numbers the barometric one B and the magnetic barometric one Bm. At the field strength, where the latter exceeds the former, instability sets in. We discuss the growth rate of linear perturbations and the amplitude of nonlinear stationary convection rolls. The latter is governed by the balance of concentration advection and sedimentation.