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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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01 Jan 1988
TL;DR: In this paper, the authors describe the transition behavior of natural feldspars for a wide temperature range using simple Landau expansions, where two order parameters are frequently required to describe the individual contributions of atomic displacements and Al/Si ordering effects; coupling between them occurs via the spontaneous strain and may be effectively bilinear or biquadratic.
Abstract: Landau theory provides the basis for a unified thermodynamic treatment of structural phase transitions in minerals. It has recently been used, with effect, to describe the excess thermodynamic properties due to displacive and Al/Si ordering transitions in feldspars by Salje and coworkers. Semi-flexible T-O-T bonds (T = Al, Si) in the framework of the feldspar structure allow the influence of local site configurations to extend over large correlation lengths. As a consequence, the transition behaviour of natural feldspars can be described for a wide temperature range using simple Landau expansions. Two order parameters are frequently required to describe the individual contributions of atomic displacements and Al/Si ordering effects; coupling between them occurs via the spontaneous strain and may be effectively bilinear or biquadratic. These concepts, which are relatively new to earth sciences, are introduced, and their application to the thermodynamic analysis of alkali feldspar and plagioclase feldspar solid solutions is outlined. Emphasis is placed on data obtained by calorimetric methods.
52 citations
TL;DR: Using a Ginzburg-Landau free energy for oil-water-surfactant mixtures, this article showed that the Helfrich Hamiltonian describes the free energy of the amphiphilic monolayers at the oil/water interface, and calculated the bending rigidity, the saddle splay modulus and the spontaneous radius of curvature.
Abstract: Using a Ginzburg-Landau free energy for oil-water-surfactant mixtures, we show that the Helfrich Hamiltonian describes the free energy of the amphiphilic monolayers at the oil/water interface, and calculate the bending rigidity, the saddle splay modulus and the spontaneous radius of curvature. The results are used to discuss the phase diagram obtained from Landau theory, which contains a lamellar phase, a hexagonal phase of cylinders, and a droplet crystal. It is found that the interaction of the monolayers plays an important role in stabilizing the lamellar phase.
51 citations
29 Oct 1998
TL;DR: In this article, a pedagogical introduction to multidimensional bosonization is given, emphasizing its applicability in spatial dimensions greater than one and its ability to be used in many-body theory.
Abstract: Bosonization of degenerate fermions yields insight both into Landau Fermi liquids, and into non-Fermi liquids We begin our review with a pedagogical introduction to bosonization, emphasizing its applicability in spatial dimensions greater than one After a brief historical overview, we present the essentials of the method Well known results of Landau theory are recovered, demonstrating that this new tool of many-body theory is robust Limits of multidimensional bosonization are tested by considering several examples of non-Fermi liquids, in particular the composite fermion theory of the half-filled Landau level Nested Fermi surfaces present a different challenge, and these may be relevant in the cuprate superconductors We conclude by discussing the future of multidimensional bosonization
51 citations
TL;DR: In this paper, the minima of the Ginzburg-landau functional for dense neutron matter was shown to be in the same region of parameter space as the BCS functional, where the free energy is minimized by any unitary order parameter.
Abstract: We first find the minima of the general Ginzburg-Landau functional for $^{3}P_{2}$ pairing. The BCS functional lies in a region of the Ginzburg-Landau parameter space where the free energy is minimized by any unitary order parameter. We next estimate the strong-coupling corrections to the BCS functional for dense neutron matter. Using current theoretical values for the transition temperature and Landau parameters, we find that the strong-coupling functional remains in the same region of parameter space as the BCS functional.
51 citations
TL;DR: In this paper, the growth rates of modes and associated behavior in a Fermi liquid unstable to density fluctuations are studied by using Landau theory, and the hydrodynamic and collosionless limits are bridged by treating the collision integral in the relaxation-time approximation.
51 citations