Correlations between nanoscale chemical and polar order in relaxor ferroelectrics and the lengthscale for polar nanoregions

Molecular-dynamics simulations of a first-principles Hamiltonian for the model relaxor ferroelectric Pb(Sc1/2Nb1/2)O-3 were used to determine the nature of correlations between chemical and polar short-range order. Relative to chemically disordered regions (CDRs), chemically ordered regions (CORs) exhibit enhanced polarization, and polarization fluctuations at all temperatures. Magnitudes of pairwise cluster-cluster polarization correlations follow the trend COR-COR, COR-CDR, CDR-CDR correlations. This result implies that the characteristic lengthscale for polar nanoregions is the same as for chemical short-range order.