Microscopic flexoelectricity in the canonical PMN relaxor

Abstract

Previously reported neutron scattering investigations of the canonical relaxor ferroelectric perovskite oxide with the chemical formula Pb(Mg1/3Nb2/3)O3 (PMN) are revisited to appreciate the role of the intrinsic bulk flexoelectricity. Despite the outstanding electromechanical properties of lead-based relaxors, the magnitude of the flexoelectric coupling coefficient f11 − f12 ≈ −2 V, derived here directly from the PMN neutron diffuse scattering data, does not exceed the range of values typical for conventional perovskite ferroelectrics. We explain how these findings are related in the framework of the Ginzburg–Landau–Devonshire and the ferroelectric soft mode theory. We propose that the relaxor properties of PMN might be related to the suppression of the transverse correlation length of the flexoelectrically hybridized translational–polarization fluctuations due to its closeness to the Lifshitz-point regime.