Local Polarization Distribution and Edwards-Anderson Order Parameter of Relaxor Ferroelectrics

Abstract

The temperature dependence of the Edwards-Anderson order parameter ${q}_{\mathrm{EA}}$ and the local polarization distribution function $W(\stackrel{\ensuremath{\rightarrow}}{p})$ have been determined in a PMN single crystal via 2D ${}^{93}\mathrm{Nb}$ NMR. A glasslike freezing of reorientable polar clusters occurs in the temperature range of the diffuse relaxor transition, whereas the NMR spectra corresponding to pinned nanodomains do not change with temperature. The obtained form of $W(\stackrel{\ensuremath{\rightarrow}}{p})$ as well as the temperature dependence of ${q}_{\mathrm{EA}}$ and the nonlinear dielectric susceptibility can be well described by a newly proposed spherical random bond--random field model of relaxor ferroelectrics.