Landau theory

About: Landau theory is a research topic. Over the lifetime, 2882 publications have been published within this topic receiving 57078 citations.

Modelling hysteretic behaviour in magnetorheological fluids and dampers using phase-transition theory

Abstract: A dynamical mathematical model is proposed to model the hysteretic behaviour of magnetorheological fluids and dampers using phase-transition theory. To construct the model involving hysteresis, the magnetorheological fluids are assumed to be switchable between different phases upon the application of a shear strain rate, with one solid-like phase and two fluid-like phases. The Landau theory for phase transition is employed to model the dynamics of the phase transition in the fluids. The proposed model is able to capture hysteresis loops, and is rate dependent (frequency dependent). A comparison between predicted and experimental behaviour of the damper is presented, and perfect agreement is obtained.

Incommensurate phase transitions in ferroelectrics

Abstract: Fundamental aspects of incommensurate phase transitions and related physical properties in several typical ferroelectrics are reviewed within the Landau theory Collective modes in INC-phase are mentioned

Superconductors with topological order

Abstract: We propose a mechanism of superconductivity in which the order of the ground state does not arise from the usual Landau mechanism of spontaneous symmetry breaking but is rather of topological origin. The low-energy effective theory is formulated in terms of emerging gauge fields rather than a local order parameter and the ground state is degenerate on topologically non-trivial manifolds. The simplest example of this mechanism of superconductivity is concretely realized as global superconductivity in Josephson junction arrays.

Paraelectric, piezoelectric and pyroelectric crystals: II Phase transitions

Abstract: For pt. I, see ibid., vol. 6, 121 (1973). The response of a crystal in the neighbourhood of a structural phase transition is discussed. It is shown that the behaviour of the scattering cross section is very dependent upon the symmetry of the two phases. The weakly anharmonic crystal model is used within the framework of the Landau theory of phase transitions to discuss nonpiezoelectric/ ferroelectric, piezoelectric/ferroelectric and transitions involving an increase in the size of the unit cell both of the improper ferroelectric kind and otherwise. In every case it is shown that the theory gives rise to the possibility of quasi-elastic as well as inelastic scattering below Tc, but above Tc quasi-elastic scattering is expected in the piezoelectric/ferroelectric and improper ferroelectric phase transitions.