We propose to investigate the interplay of magnetic and structural properties in the multiferroic PbFe1/2Nb1/2O3 (PFN). PFN is the magnetic analogue of the archetypal lead based relaxor ferroelectrics. PFN at ambient pressure displays structural diffuse scattering (characteristic of local polar correlations) onset at ~400 K and magnetic diffuse correlations below 150 K. The magnetic and ferroelectric order parmeters are expected to be coupled through strain and indeed chemical pressure results in dramatic changes in the magnetic and structural properties. We therefore propose to use mechanical pressure on PEARL to controlably tune the coupled magnetic and polar correlations.