### Session Y22: Ferroelectric and Structural Phase Transitions

8:00 AM–11:00 AM, Friday, March 25, 2011
Room: D163

Chair: Jason Lashley, Los Alamos National Laboratory

Abstract ID: BAPS.2011.MAR.Y22.13

### Abstract: Y22.00013 : Microstructure from ferroelastic transitions using strain pseudospin clock models in two and three dimensions

10:24 AM–10:36 AM

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#### Authors:

Turab Lookman
(Los Alamos National Laboratory)

Romain Vasseur
(Ecole Normale Superieur, Paris)

Subodh Shenoy
(School of Physics, University of Hyderabad)

We show how microstructure can arise in first-order ferroelastic structural transitions, in two and three spatial dimensions, through a local mean-field approximation of their pseudospin Hamiltonians, that include anisotropic elastic interactions. Such transitions have symmetry-selected physical strains as their order parameters, with Landau free energies that have a single zero-strain austenite'' minimum at high temperatures, and spontaneous-strain martensite'' minima of structural variants at low temperatures. The total free energy also has gradient terms, and power-law anisotropic effective interactions, induced by no-dislocation'' St Venant compatibility constraints. In a reduced description, the strains at Landau minima induce temperature dependent, clocklike Hamiltonians, with strain- pseudospin vectors S pointing to discrete values including zero. We study elastic texturing in five such first-order structural transitions through a local mean-field approximation of their pseudospin Hamiltonians, that include the power-law interactions. The local mean-field solutions in 2D and 3D yield or oriented domain- wall patterns as from continuous-variable strain dynamics, showing the discrete- variable models capture the essential ferroelastic texturings.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2011.MAR.Y22.13