Pseudospin model of above-barrier states in a three-component multiple-sublattice crystal

A model of a structurally disordered crystal with three equivalent states per site is studied. An effective pseudospin model Hamiltonian which takes account of above-barrier motion is constructed. An expression is obtained for the nonequilibrium free energy for one- and four-sublattice ordering. The...

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Bibliographic Details
Published in:Low temperature physics (Woodbury, N.Y.) N.Y.), 2008-03, Vol.34 (3), p.216-222
Main Authors: Kovarskiĭ, V. L., Kuznetsov, A. Yu
Format: Article
Language:English
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Summary:A model of a structurally disordered crystal with three equivalent states per site is studied. An effective pseudospin model Hamiltonian which takes account of above-barrier motion is constructed. An expression is obtained for the nonequilibrium free energy for one- and four-sublattice ordering. The state of metastable disorder for a one-sublattice structure and an equilibrium phase transition for a four-sublattice model are studied. The results are used to interpret Mössbauer studies of the Jahn–Teller crystal Cu ( H 2 O ) 6 ⋅ Si F 6 . A theoretical explanation is given for the statics-dynamics transition, observed in the disordered phase of this crystal as the structural phase transition point is approached.
ISSN:1063-777X
1090-6517
DOI:10.1063/1.2887866