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Novel Surface State In A Class Of Incommensurate Systems, A. E. Jacobs, D. Mukamel, David W. Allender
Novel Surface State In A Class Of Incommensurate Systems, A. E. Jacobs, D. Mukamel, David W. Allender
David W Allender
We study the Landau model of the class of incommensurate systems with a scalar order parameter where the modulated phase is driven by a gradient-squared term with negative coefficient. For example, theoretical studies of cholesteric liquid crystals in a field (electric or magnetic) suggest that such an modulated phase should exist at high chirality. The bulk phase diagram in the presence of a bulk external field which couples linearly to the order parameter exhibits a modulated phase inside a loop in the temperature-field plane, and a homogeneous phase outside. On analyzing the same model for a semi-infinite system, we find …
Surface States In Nearly Modulated Systems, A. E. Jacobs, D. Mukamel, David W. Allender
Surface States In Nearly Modulated Systems, A. E. Jacobs, D. Mukamel, David W. Allender
David W Allender
A Landau model is used to study the phase behavior of the surface layer for magnetic and cholesteric liquid-crystal systems that are at or near a Lifshitz point marking the boundary between modulated and homogeneous bulk phases. The model incorporates surface and bulk fields and includes a term in the free energy proportional to the square of the second derivative of the order parameter in addition to the usual term involving the square of the first derivative. In the limit of vanishing bulk field, three distinct types of surface ordering are possible: a wetting layer, a nonwet layer having a …