Phenomenological Description of the Acoustic Phonon Branch of K2SeO4

A phenomenological approach is used in investigating dispersion of the acoustic phonon branch of K 2 SeO 4 in the extended zone scheme. The dispersion is expressed through coefficients of a simple thermodynamic potential. According to symmetry of the crystal (D 2h = mmm) the Lifshitz-type invariant...

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Bibliographic Details
Published in:Ferroelectrics 2004-01, Vol.302 (1), p.147-150
Main Authors: SANNIKOV, D. G., MASHIYAMA, H.
Format: Article
Language:English
Subjects:
acoustic branch
Phenomenological approach
SeO
Online Access:Get full text
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Summary:A phenomenological approach is used in investigating dispersion of the acoustic phonon branch of K 2 SeO 4 in the extended zone scheme. The dispersion is expressed through coefficients of a simple thermodynamic potential. According to symmetry of the crystal (D 2h = mmm) the Lifshitz-type invariant exists in the potential. This invariant is responsible for the linear and dynamical interaction of the acoustic and optical branches. The soft optical branch lowering with decreasing temperature forces to lower the acoustic branch which becomes zero at some value of the wave vector.
ISSN:0015-0193
1563-5112
DOI:10.1080/00150190490453351