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Landau theory
About: Landau theory is a research topic. Over the lifetime, 2882 publications have been published within this topic receiving 57078 citations.
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TL;DR: In this article, a detailed discussion of the predictions of the Landau-Devonshire theory for the behavior of thin ferroelectric films is given, assuming that the phase transition in the bulk is second order.
Abstract: A detailed discussion is given of the predictions of the Landau-Devonshire theory for the behavior of thin ferroelectric films. It is assumed that the phase transition in the bulk is second order, and the theory is extended by the inclusion in the free-energy density of a term proportional to $|\ensuremath{
abla}P{|}^{2}$ together with a boundary condition involving an extrapolation length \ensuremath{\delta}. Expressions for the polarization profile $P(z)$ are given in terms of Jacobi elliptic functions; some of these are in a clearer and simpler form than has been available previously. Interesting analytic results for the entropy in terms of elliptic integrals and elliptic functions are also presented. Graphical illustrations of the main results are included. Careful consideration is given to the nature of the phase transition, and it is concluded that it is second order in all cases.
69 citations
TL;DR: This work demonstrates the divergence in the behavior of the compressibility near the density driven Mott transition at finite temperatures using DMFT and quantum Monte Carlo simulations in the one-band and the two-band Hubbard model.
Abstract: In the context of the dynamical mean-field theory (DMFT) of the Hubbard model, we study the behavior of the compressibility near the density driven Mott transition at finite temperatures. We demonstrate this divergence using DMFT and quantum Monte Carlo simulations in the one-band and the two-band Hubbard model. We supplement this result with considerations based on the Landau theory framework, and discuss the relevance of our results to the alpha-gamma end point in cerium.
68 citations
TL;DR: The convective and potential variational principles that can be used for alternative derivations of the same natural relativistic generalisation of the standard Landau theory of perfect superfluid dynamics are both characterised by the feature that, instead of attributing special importance to a partition in terms of certain nonconserved "superfluid" and "normal" current vectors j S ν and j N ν, they accord a much more prominent role to certain particle and momentum covectors.
68 citations
TL;DR: The Landau theory of shape transitions in hot rotating nuclei is introduced and the universal features of such transitions are derived and the theory is used to calculate the phase diagram of the /sup 166/Er nucleus.
Abstract: The Landau theory of shape transitions in hot rotating nuclei is introduced and the universal features of such transitions are derived. The phase diagram of the excitation energy versus angular momentum J for nuclei with prolate ground states shows a transition line from triaxial to oblate shapes. The transition is first order for small values of J and becomes second order above a certain value which is the analog of the tricritical point. Nuclear shapes change very rapidly from near prolate to oblate in the vicinity of this point. The theory is used to calculate the phase diagram of the /sup 166/Er nucleus.
68 citations
TL;DR: A density-functional theory for the isotropic-nematic transition of hard ellipsoids is proposed which is in fair quantitative agreement with the recent computer simulations of this system and which improves considerably upon the earlier theoretical attempts.
Abstract: We propose a density-functional theory for the isotropic-nematic transition of hard ellipsoids which is in fair quantitative agreement with the recent computer simulations of this system and which improves considerably upon the earlier theoretical attempts. The theory has an explicit oblate-prolate symmetry and leads to simple analytic expressions, e.g., for the equation of state of the isotropic phase. When the free energy of the nematic phase is expanded with respect to the Maier-Saupe quadrupole order parameter, an explicit Landau theory is produced, which is shown to underscore considerably the strength and the width of the transition. A virial expansion of the free energy produces in turn an Onsager theory for finite elongations whose results are shown to tend only very slowly to their Onsager limiting value. We also propose a Lindemann rule for orientational freezing.
67 citations