Antiphase structures of an improper ferroelastic phase transition driven by an M5- zone boundary phonon in RAg1-xInx

Wenwu Cao, Avadh Saxena, Dorian M. Hatch

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Abstract

Rare-earth alloys RAg1-xInx (where R=La, Ce, and Pr) are improper ferroelastic materials with the CsCl structure. A weakly first-order phase transition occurs with the softening of a zone-edge M5- mode that drives the material from a cubic phase to a tetragonal phase. Based on Ginzburg-Landau theory, we utilize the complete free-energy density, constructed from a six-dimensional primary order parameter (shuffle) that couples to strain, to study domain formation. The model allows the study of complex antiphase structures that appear in this cubic-to-tetragonal phase transition. With the help of numerical techniques, the order-parameter profiles across antiphase boundaries of different orientations and their temperature dependence are calculated. We find a single set of two coupled dimensionless governing equations, which are applicable to order-parameter profiles across all antiphase boundaries for this transition.

Original languageEnglish (US)
Article number024106
Pages (from-to)241061-2410612
Number of pages2169552
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume64
Issue number2
DOIs
Publication statusPublished - Jan 1 2001

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All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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