Response of Polar Nanoregions in the Relaxor Ferroelectric PZN-8\%PT to an Electric Field

We report measurements of the neutron diffuse scattering from a single crystal of the relaxor ferroelectric PbZn$_{1/3}$Nb$_{2/3}$O$_3$ doped with 8\% PbTiO$_3$ (PZN-8PT) for temperatures 100K $\le T \le$ 550K and electric fields 0kV/cm $\le E \le$ 10kV/cm oriented along [001]. The diffuse scattering near the (300) and (003) Bragg peaks, which is strong for this system, was measured in both zero field cooled and field cooled conditions [1]. In all cases we find the surprising result that the diffuse scattering is not eliminated by electric fields up to 10 kV/cm, but is instead approximately preserved. However the reciprocal space geometry, or ``shape," of the diffuse scattering is modified. Thus field-cooling PZN-8\%PT into the tetragonal (ferroelectric) phase does not produce a uniformly polarized state. Measurements were also made to confirm the interesting memory effect in PZN-8PT reported by Xu {\it et al.} under a [111]-oriented field [2]. [1] P.M. Gehring, K. Ohwada, and G. Shirane, Phys. Rev. B {\bf 70}, 014110 (2004). [2] Guangyong Xu, P.M. Gehring, and G. Shirane, submitted to Science.