  We establish the nonequilibrium thermal phases of a voltage driven
antiferromagnetic Mott insulator in three dimensions, realised at steady state
under a voltage bias. Starting from the Keldysh action for the half filled
Hubbard model we derive an effective Langevin equation for the `slow' magnetic
variables. The coupling of electrons to these degrees of freedom determine the
transport properties. At low temperature we find a voltage-driven discontinuous
insulator-metal transition, along with hysteresis. We map the suppression of
the N\'eel temperature $T_N$ and pseudogap temperature $T_{pg}$ with increasing
voltage, and discover that the biased Mott insulator has a finite temperature
insulator-metal transition. The low temperature results resolve an experimental
puzzle about hysteresis, and the thermal results make testable predictions on
spectra and nonlinear transport.
