Phase transitions and free energy expansion: Landau theory in a nutshell

2014 ◽  
pp. 462-468
Author(s):  
Daniel I. Khomskii
Keyword(s):  
Free Energy ◽  
Phase Transitions ◽  
Landau Theory ◽  
Energy Expansion

Phase Diagrams for Incommensurate Systems

1982 ◽  
Vol 21 ◽  
Author(s):  
P. Toledano
Keyword(s):  
Free Energy ◽  
Phase Transitions ◽  
Energy Density ◽  
Phase Diagrams ◽  
Order Parameter ◽  
Landau Theory ◽  
Free Energy Density ◽  
Lock In

ABSTRACTPhase diagrams, for systems undergoing one or several incommensurate and lock-in transitions, are discussed in the framework of the Landau theory of phase transitions. It is shown that their essential features can be deduced from the explicit forms of the free-energy density ø and the k-dispersion of the coefficient α(→k)of the quadratic contribution of the order-parameter components in ø. Two families of phase diagrams are distinguished depending on symmetry considerations.

Phase Diagrams of Ni2MnX (X = In, Sn, Sb) Heusler Alloys with Inversion of Exchange Interaction

2008 ◽  
Vol 583 ◽  
pp. 131-146 ◽  
Author(s):  
Vasiliy D. Buchelnikov ◽  
Sergey Taskaev ◽  
M.A. Zagrebin ◽  
Peter Entel
Keyword(s):  
Free Energy ◽  
Phase Transitions ◽  
Exchange Interaction ◽  
Phase Diagrams ◽  
Magnetic Phase ◽  
Landau Theory ◽  
Heusler Alloys ◽  
Magnetic Phase Transitions ◽  
Experimental Phase ◽  
Ginzburg Landau

In this work with the help of the phenomenological Ginzburg-Landau theory of structural and magnetic phase transitions the phase diagrams of Heusler Ni-Mn-X (X = In, Sn, Sb) alloys with the inversion of exchange interaction are investigated. The investigation shows that the type of the phase diagrams in Heusler Ni-Mn-X (X = In, Sn, Sb) alloys depends on the value and sign of the free energy parameters. As it is seen from the analysis of the phase diagrams with the determined values and signs of the parameters of Landau functional there are thermodynamic paths which allow to explain experimental phase transitions in Heusler alloys Ni-Mn-X (X = In, Sn, Sb) and Ni-Co- Mn-X (X = In, Sn, Sb) qualitatively.

Thermodynamic Formalism and Phase Transitions of Generalized Mean-Field Quantum Lattice Models

1998 ◽  
Vol 53 (5) ◽  
pp. 179-207
Author(s):  
T. Gerisch ◽  
A. Rieckers ◽  
H.-J. Volkert
Keyword(s):  
Free Energy ◽  
Phase Transitions ◽  
Energy Density ◽  
Landau Theory ◽  
Thermodynamic Formalism ◽  
Free Energy Density ◽  
Equilibrium States ◽  
Minimal Free Energy ◽  
Symmetry Properties ◽  
Quantum Statistical

The general structure of thermodynamic equilibrium states for a class of quantum mechanical (multi-lattice) systems is elaborated, combining quantum statistical and thermodynamical methods. The quantum statistical formulation is performed in terms of recent operator algebraic concepts emphasizing the role of the permutation symmetry due to homogeneous coarse graining and employing the internal symmetries. The variational principle of the free energy functional is derived, which determines together with the symmetries the general form of the limiting Gibbs states in terms of their central decomposition. The limiting minimal free energy density and its possible equilibrium states are analyzed on various levels of the description by means of convex analysis, where the Fenchel transforms of the free energies provide entropy like potentials. On the thermodynamic level a modified entropy surface is obtained, which specifies only in combination with its concave envelope the regions of pure and mixed phase states. The symmetry properties of a certain model allow to specify the (non-) differentiability of the minimal free energy density. A characterization and classification of phase transitions in terms of quantum statistical equilibrium states is proposed, and the connection to the Landau theory is established demonstrating that the latter implies a (continuous) deformation of the sets of equilibrium states along a canonically given curve.

Landau theory of phase transitions in TTF-TCNQ

1980 ◽  
Vol 41 (7) ◽  
pp. 677-699 ◽  
Author(s):  
C. Hartzstein ◽  
V. Zevin ◽  
M. Weger
Keyword(s):  
Phase Transitions ◽  
Landau Theory

Optimal approaches to manage power system decarbonation

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1447-1452
Author(s):  
Vincent Mazauric ◽  
Ariane Millot ◽  
Claude Le Pape-Gardeux ◽  
Nadia Maïzi
Keyword(s):  
Free Energy ◽  
Linear Programming ◽  
Phase Transitions ◽  
Power System ◽  
Energy System ◽  
Energy Sources ◽  
Low Carbon ◽  
Faraday’S Law ◽  
Optimal Description ◽  
Low Carbon Technologies

To overcome the negative environemental impact of the actual power system, an optimal description of quasi-static electromagnetics relying on a reversible interpretation of the Faraday’s law is given. Due to the overabundance of carbon-free energy sources, this description makes it possible to consider an evolution towards an energy system favoring low-carbon technologies. The management for changing is then explored through a simplified linear-programming problem and an analogy with phase transitions in physics is drawn.

Landau theory of second-order phase transitions in ferroelectric films

2001 ◽  
Vol 63 (14) ◽  
Author(s):  
Lye-Hock Ong ◽  
Junaidah Osman ◽  
D. R. Tilley
Keyword(s):  
Phase Transitions ◽  
Landau Theory ◽  
Second Order ◽  
Ferroelectric Films
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