Role of Fluctuations in the Coherent Displacements of Atomic Equilibrium Positions at Second-Order Phase Transitions

Authors

  • Z. P. Mastropas Southern Federal University
  • E. N. Myasnikov Southern Federal University

DOI:

https://doi.org/10.15407/ujpe58.06.0573

Keywords:

thermodynamic potential, structure transformation, electron-phonon interaction, oscillation mode, wave function, deformation, Hamiltonian, Green function

Abstract

Second-order phase transitions in ferroics of the ferroelastic type have been studied theoretically. The temperature-induced phase transition in crystals with a wide forbidden gap caused by the interaction between electrons and a branch of acoustic vibrations in the crystal lattice is considered. The vertex part of this interaction with transverse lattice vibrations is calculated. The characteristic features of the thermodynamic potential at the transition point and the temperature dependence of the acoustic phonon dispersion at the transition over quasiequilibrium states are discussed. It is shown that the stabilization of structure fluctuations by the electron subsystem in the high-symmetry phase, and a reduction of soft mode frequencies makes those fluctuations metastable.

UJP 2013 V58 #6

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Published

2018-10-10

Issue

Vol. 58 No. 6 (2013)

Section

Solid matter

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How to Cite

Role of Fluctuations in the Coherent Displacements of Atomic Equilibrium Positions at Second-Order Phase Transitions. (2018). Ukrainian Journal of Physics, 58(6), 573. https://doi.org/10.15407/ujpe58.06.0573