Showing papers on "Landau theory published in 1968"
151 citations
TL;DR: In this article, a simple molecular field theory is developed to explain at least qualitatively the behaviour of weakly ferromagnetic and strongly paramagnetic alloys near their critical concentration c F.
Abstract: A simple molecular field theory is developed to explain at least qualitatively the behaviour of weakly ferromagnetic and strongly paramagnetic alloys near their critical concentration c F . The free energy of a weakly ferromagnetic alloy can be expanded in powers of magnetization ζ and a modified Landau theory is used to calculate the concentration dependence of the magnetization, specific heat and the susceptibility near c F . It is believed that such a theory can work better in this case than does the usual Landau theory as fluctuations in ζ are relatively small for low temperatures. A change in low temperature resistivity around c F is also expected as a result of ciritcal scattering of conduction electrons. This change was first calculated by Rice (1967) for strongly paramagnetic alloys giving a large T 2 term. However, this calculation is not applicable for c very close to c F . It is shown that for c → c F the paramagnetic resistivity remains finite and has a maximum for c ═ c F , ρ Para c ═ c F ∝ T 5/3 . It is also found that the ferromagnetic resistivity ρ ferro has a similar dependence on concentration and temperature as ρ Para and ρ ferro c ═ c F ═ ρ Para c ═ c F , i.e. the resisitivity is symmetrical around c F .
79 citations
TL;DR: A special type of Landau theory of second order phase transitions allows the incorporation of spatial fluctuations of the order parameter in a consistent way as discussed by the authors, which describes the thermal properties of He II nearTλ in agreement with experiment.
Abstract: A special type of Landau theory of second order phase transitions allows the incorporation of spatial fluctuations of the order parameter in a consistent way. The resulting theory describes the thermal properties of He II nearTλ in agreement with experiment.
11 citations
TL;DR: In this paper, the properties of iron at its ferromagnetic transition point were described by a type of Landau-theory developed for He II. The theory includes spatial fluctuations of the spontaneous magnetisation which lead to a logarithmic singularity of the specific heat nearTc in agreement with measurements byKraftmakher andRomashina.
Abstract: The properties of iron at its ferromagnetic transition point are described by a type of Landau-theory developed for He II. The theory includes spatial fluctuations of the spontaneous magnetisation which lead to a logarithmic singularity of the specific heat nearTc in agreement with measurements byKraftmakher andRomashina.
9 citations
TL;DR: In this article, a generalized Landau functional for the thermodynamic potential near a continous phase transition was constructed, which reproduces all critical-exponent scaling relations, and a consistency test of the theory is either satisfied throughout the critical region or nowhere.
7 citations
TL;DR: In this article, the symmetrized cube and the antisymmetric square of the irreducible representations of the point groups are reduced and tabulated; these are the products which are relevant to Landau's theory of second-order phase transitions.
Abstract: The symmetrized cube and the antisymmetrized square of the irreducible representations of the point groups are reduced and tabulated; these are the products which are relevant to Landau's theory of second-order phase transitions.
7 citations
3 citations