This experiment seeks to continue previous work on PEARL, whereby the phase is altered in the room temperature multiferroic BiFeO3 - PbTiO3 using hydrostatic pressure with the onset of magnetic ordering. This is possible in this system as, within one composition, the rhombohedral and tetragonal phases have a density which differs by over 5%.This effect is extremely exiting, as it provides direct evidence of a mechanism of magnetoelectric coupling. Key objectives are to study a range of materials, fine tuned to allow phase switching at far lower pressures (<100 compared to 700 MPa) than in previous experiments.