  We study nonequilibrium steady states in a holographic superconductor under
time periodic driving by an external rotating electric field. We obtain the
dynamical phase diagram. Superconducting phase transition is of first or second
order depending on the amplitude and frequency of the external source. The
rotating electric field decreases the superconducting transition temperature.
The system can also exhibit a first order transition inside the superconducting
phase. It is suggested this transition exists all the way down to zero
temperature. The existence of nonequilibrium thermodynamic potential for such
steady solutions is also discussed from the holographic point of view. The
current induced by the electric field is decomposed into normal and
superconducting components, and this makes it clear that the superconducting
one dominates in low temperatures.
