The impact of magnetoelasticity on structural phase transitions in cubic ferromagnets
Influence of the magnetoelastic interaction on the structural phase transitions in cubic ferromagnets is investigated on the basis of a Ginzburg-Landau theory. It is shown that for the case of a positive magnetic anisotropy constant the structural phase transitions are not accompanied by a spin-reorientation. In the magnetic state the high-temperature phase has small deformations caused by the magnetostriction. For the case of a strong magnetoelastic coupling these deformations lead to vanishing of the first order structural transitions. Corresponding critical points are determined. Due to the magnetoelastic interaction a first order magnetic phase transition can occur simultaneously with a structural first order transformation. The constrained theory allows to calculate a realistic (T,x)-phase diagram for Ni2+xMn1−xGa alloys. 64.10.+h, 64.70.Kb, 75.30.Gw, 75.80.+q Typeset using REVTEX 1
The Landau theory of phase transitions: A mechanical analog
The Landau theory of phase transitions occupies a centerpiece position in physics. We illustrate the theory by a pedagogical example at the pre-university level. In the example a bead of mass is threaded on a ring which is set rotating about a vertical diameter. The dynamics of the bead mimics key features of the Landau theory.
L. D. Landau’s plain talk to students of physics
This article was published in 1971 in the Russian journal Science and Life. Teachers and students who read our Journal can profit from the advice of this master theoretician. We are grateful to E. M. Lifshitz and the editor of Science and Life for permission to publish the article and particularly to J. George Adashko for preparing the translation.