Acoustic collective excitations and static dielectric response in incommensurate crystals with real order parameter

Starting from the basic Landau model for the incommensurate-commensurate materials of the class II, we derive the spectrum of collective modes for all (meta)stable states from the corresponding phase diagram. It is shown that all incommensurate states posses Goldstone modes with acoustic dispersions...

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Bibliographic Details
Published in:arXiv.org 2000-05
Main Authors: Dananic, V, Bjelis, A, Latkovic, M
Format: Article
Language:English
Subjects:
Brillouin zones
Order parameters
Phase diagrams
Online Access:Get full text
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Summary:Starting from the basic Landau model for the incommensurate-commensurate materials of the class II, we derive the spectrum of collective modes for all (meta)stable states from the corresponding phase diagram. It is shown that all incommensurate states posses Goldstone modes with acoustic dispersions. The representation in terms of collective modes is also used in the calculation and discussion of static dielectric response for systems with the commensurate wave number in the center of the Brillouin zone.
ISSN:2331-8422