A possible scenario for two soft branches in PMN

0365357 - FZÚ 2012 RIV GB eng J - Journal Article
Kempa, Martin - Hlinka, Jiří
A possible scenario for two soft branches in PMN.
Phase Transitions. Roč. 84, 9-10 (2011), s. 784-788. ISSN 0141-1594. E-ISSN 1029-0338
R&D Projects: GA ČR GAP204/10/0616
Institutional research plan: CEZ:AV0Z10100520
Keywords : PMN relaxor * waterfall phenomenon * phonon dispersions * inelastic scattering
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 1.006, year: 2011

The acoustic–optic mode coupling model in lead-based perovskite relaxors has been extended by taking into account the two-component nature of the lowest frequency optic phonon mode. Inelastic scattering spectral function and the course of the apparent phonon dispersion branches were calculated for parameters relevant to Pb(Mg1/3Nb2/3)O3 (PMN) relaxor. Dynamical parameters of the zone-centre soft mode components in the problematic region around the Burns temperature have been described with the help of the recent hyper-Raman scattering study on PMN. We show that the vertical dispersion (waterfall anomaly) is primarily due to the coupling of the transverse acoustic branch to the lower frequency component of the TO1 phonon branch. As in the inelastic neutron scattering experiments, in this model the temperature interval in which the waterfall anomaly appears is roughly restricted by the freezing and Burns temperatures.
Permanent Link: http://hdl.handle.net/11104/0200617