Previous Landau-type models of two-phase state formation in clamped systems whose material exhibits first-order phase transitions in free state neglects the existence of interphase boundaries. Here, we take them into account in the framework of a Ginzburg–Landau one-dimensional model to study the dependence of characteristics of the two-phase state on system size. Unlike earlier works, we find that the transition to the two-phase state from both the symmetrical and nonsymmetrical phases is not continuous but abrupt. For a one-dimensional system with length L studied in this work, we show that the formation of two-phase state begins with a region whose size is proportional to . The latent heat of the transition is also proportional to so that the specific latent heat goes to zero as , recovering the earlier result for infinite systems. The temperature width of the two-phase region decreases with decreasing of , but we are unable to answer the question about the critical length for two-phase state formation because the approximation used in analytical calculations is valid for sufficiently large L. A region of small values of L was studied partially to reveal the limits of validity of the analytical calculations. The main physical results are also obtainable within a simple approximation that considers the energy of interphase boundary as a fixed value, neglecting its temperature dependence and the thickness of the boundary. A more involved but consistent treatment provides the same results within the accepted approximation and sheds light on the reason of validity of the simplified approach.
Effects of interphase boundaries in Ginzburg–Landau one-dimensional model of two-phase states in clamped systems
Note: This paper is part of the Special Topic on Domains and Domain Walls in Ferroic Materials.
Arkady P. Levanyuk, Sergey A. Minyukov, I. Burc Misirlioglu, M. Baris Okatan; Effects of interphase boundaries in Ginzburg–Landau one-dimensional model of two-phase states in clamped systems. J. Appl. Phys. 28 January 2021; 129 (4): 044102. https://doi.org/10.1063/5.0029144
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