We report neutron inelastic scattering experiments on single crystal PbMg1/3Nb2/3O3 doped with 32\% PbTiO3, a relaxor ferroelectric that lies close to the morphotropic phase boundary. When cooled under an electric field E∥ [001] into tetragonal and monoclinic phases, the scattering cross section from transverse acoustic (TA) phonons polarized parallel to E weakens and shifts to higher energy relative to that under zero-field-cooled conditions. Likewise, the scattering cross section from transverse optic (TO) phonons polarized parallel to E weakens for energy transfers 4≤ℏω≤9 meV. However, TA and TO phonons polarized perpendicular to E show no change. This anisotropic field response is similar to that of the diffuse scattering cross section, which, as previously reported, is suppressed when polarized parallel to E, but not when polarized perpendicular to E. Our findings suggest that the lattice dynamics and dynamic short-range polar correlations that give rise to the diffuse scattering are coupled.
@article{arxiv.1509.07085,
title = {Phonon coupling to dynamic short-range polar order in a relaxor ferroelectric near the morphotropic phase boundary},
author = {John A. Schneeloch and Zhijun Xu and B. Winn and C. Stock and P. M. Gehring and R. J. Birgeneau and Guangyong Xu},
journal= {arXiv preprint arXiv:1509.07085},
year = {2016}
}