Surface state on first-order ferroelectrics
Document Type
Article
Publication Date
1-1-2006
Abstract
In the presence of a surface the Landau-Devonshire equations of ferroelectricity must be extended to include a boundary condition. For a ferroelectric with a second-order transition in the case when the polarization p(z) increases at the surface, it is well known that a surface state occurs in a range of temperature above the bulk critical temperature t(CB) . Here we explore the corresponding effect for a first-order ferroelectric. We show that a surface state can occur, but only if the surface effect is sufficiently strong. Analytic expressions are derived and illustrated for p(z), the surface value p(S) =p(0) and the free energy. The transition from the paraelectric state (p=0) to the surface state is first order, and for completeness we establish the dependence of the three critical temperatures (supercooling, thermodynamic and superheating) on a boundary-condition parameter y. In a final section, we derive and illustrate expressions for p(z)in the temperature range t < t(CB) .
Keywords
Susceptibility tensor components, Phase-transitions, Landau theory, Films, Batio3, Computations, Particles
Divisions
PHYSICS
Publication Title
European Physical Journal B
Volume
52
Issue
1
Additional Information
Department of Physics, Faculty of Science Building, University of Malaya, 50603 Kuala Lumpur, MALAYSIA