  A quantitative estimation of the effect of simultaneously applied external
pressure (P) and magnetic field (H) on the phase coexistence has been presented
for Pr0.5Ca0.5Mn0.975Al0.025O3 and La0.5Ca0.5MnO3, where the ferromagnetic
(FM)-metal and antiferromagnetic (AFM)-insulator phases compete in real space.
We found that the nonequilibrium dynamics across the FM-AFM transition is
primarily dictated by the effect of P and H on the supercooling, superheating
temperatures, and the nucleation and growth rate of the equilibrium phase.
These effects across the transition is also responsible for the relative volume
fraction of the competing phases at low temperature. Importantly in the entire
magnetic field-pressure-temperature range of phase coexistence, the interface
between the two competing phases having different spin and structural order
plays a very important role in controlling the non-equilibrium dynamics.
