  The temperature dependent resistivity of two Pr1-xCaxMnO3 (x=0.5 and 0.4)
thin films grown on LaAlO3 has been studied as a function of hydrostatic
pressure (up to 2.5 GPa) and magnetic field (up to 9T). Both samples show a
monotonic decrease in the resistivity with an increase in pressure,
corresponding to a change of -35% at 2.5 GPa. No pressure induced
metal-to-insulator transition was observed in the temperature-dependent
resistivity. The non-trivial interaction between high pressure and magnetic
field reveals that the effect of pressure cannot be simply rescaled to that of
a specific field, as has been reported for the corresponding bulk material. We
propose an interpretation of the data based on phase separation, where two
different insulating phases coexist: the charge ordered phase, which is
sensitive to both magnetic field and pressure, and a second insulating phase
that can be tuned by magnetic field. Such a result demonstrates that phase
separation can be manipulated in thin films by independent application of
magnetic field and/or external pressure.
