[001] electric field effect on phonons in PMN-32PT*

We report inelastic neutron scattering measurements on a single crystal of the relaxor ferroelectric 68\%Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_{3}$-32\%PbTiO$_{3}$ (PMN-32PT) under an external [001] electric field (0.5 kV/cm). In addition to the partial suppression of diffuse scattering intensities, as previously reported, we also see a field-induced change in acoustic phonon intensities and energies. The change is anisotropic, with clear differences between the [100] and [001] directions. We will discuss these results and their relation to possible changes in the domain structure under field and coupling between diffuse scattering and phonon modes.