Landau Model for Commensurate-Commensurate Phase Transitions in Uniaxial Improper Ferroelectric Crystals

We propose the Landau model for lock-in phase transitions in uniaxially modulated improper ferroelectric incommensurate-commensurate systems of class I. It includes Umklapp terms of third and fourth order and secondary order parameter representing the local polarization. The corresponding phase diag...

Full description

Saved in:
Bibliographic Details
Published in:arXiv.org 2000-04
Main Authors: Latkovic, M, Bjelis, A, Dananic, V
Format: Article
Language:English
Subjects:
Algorithms
Ferroelectric crystals
Ferroelectric materials
Ferroelectricity
Lattice parameters
Order parameters
Phase diagrams
Phase transitions
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We propose the Landau model for lock-in phase transitions in uniaxially modulated improper ferroelectric incommensurate-commensurate systems of class I. It includes Umklapp terms of third and fourth order and secondary order parameter representing the local polarization. The corresponding phase diagram has the structure of harmless staircase, with the allowed wave numbers obeying the Farey tree algorithm. Among the stable commensurate phases only those with periods equal to odd number of lattice constants have finite macroscopic polarizations. These results are in excellent agreement with experimental findings in some A2BX4 compounds.
ISSN:2331-8422
DOI:10.48550/arxiv.0004166