Phase amplitude decoupling in modulated structures

We examine under what conditions phase and amplitude modulations are decoupled in a modulated structure, within a Landau Ginzburg approach. For the general case of a pth order commensurability, the condition for phase amplitude decoupling depends on the leading anharmonic terms in the Landau Ginzbur...

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Bibliographic Details
Published in:Solid state communications 1979-01, Vol.32 (12), p.1247-1250
Main Authors: Lederer, P., Medeiros, J.T.N., Theodorou, G.
Format: Article
Language:English
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Summary:We examine under what conditions phase and amplitude modulations are decoupled in a modulated structure, within a Landau Ginzburg approach. For the general case of a pth order commensurability, the condition for phase amplitude decoupling depends on the leading anharmonic terms in the Landau Ginzburg free energy. For a 2 Mth order leading anharmonic term, the case p = 2 M is a border line case. For p > 2 M, phase and amplitude are decoupled near the disordered-incommensurate transition temperature, while they are not for p < 2 M. In the latter case decoupling occurs at lower temperatures. We discuss the case of deuterated thiourea, which exhibits a commensurate pinning for p = 9 at T = 191 K.
ISSN:0038-1098
1879-2766
DOI:10.1016/0038-1098(79)90877-9