Soft mode dynamics above and below the Burns temperature in the relaxor Pb(Mg1/3Nb2/3)O3

P M Gehring; S Wakimoto; Z G Ye; G Shirane

doi:10.1103/PhysRevLett.87.277601

Soft mode dynamics above and below the Burns temperature in the relaxor Pb(Mg1/3Nb2/3)O3

Phys Rev Lett. 2001 Dec 31;87(27 Pt 1):277601. doi: 10.1103/PhysRevLett.87.277601. Epub 2001 Dec 11.

Authors

P M Gehring¹, S Wakimoto, Z G Ye, G Shirane

Affiliation

¹ NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.

PMID: 11800914
DOI: 10.1103/PhysRevLett.87.277601

Abstract

We report neutron inelastic scattering measurements of the lowest-energy transverse optic (TO) phonon branch in the relaxor Pb(Mg1/3Nb2/3)O3 from 400 to 1100 K. Far above the Burns temperature T(d) approximately 620 K we observe well-defined propagating TO modes at all wave vectors q, and a zone center TO mode that softens in a manner consistent with that of a ferroelectric soft mode. Below T(d) the zone center TO mode is overdamped. This damping extends up to, but not above, the waterfall wave vector q(wf), which is a measure of the average size of the polar nanoregions.