Browsing by Author "Chou, Y. L."
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- Ising metamagnets in thin film geometry: Equilibrium propertiesChou, Y. L.; Pleimling, Michel J. (American Physical Society, 2011-10-17)Artificial antiferromagnets and synthetic metamagnets have attracted much attention recently due to their potential for many different applications. Under some simplifying assumptions, these systems can be modeled by thin Ising metamagnetic films. In this paper we study, using both the Wang-Landau scheme and importance sampling Monte Carlo simulations, the equilibrium properties of these films. On the one hand, we discuss the microcanonical density of states and its prominent features. On the other hand, we analyze canonically various global and layer quantities. We obtain the phase diagram of thin Ising metamagnets as a function of temperature and external magnetic field. Whereas the phase diagram of the bulk system exhibits only one phase transition between the antiferromagnetic and paramagnetic phases, the phase diagram of thin Ising metamagnets includes an additional intermediate phase where one of the surface layers has aligned itself with the direction of the applied magnetic field. This additional phase transition is discontinuous and ends in a critical end point. Consequently, it is possible to gradually go from the antiferromagnetic phase to the intermediate phase without passing through a phase transition.
- Self-similarity in the classification of finite-size scaling functions for toroidal boundary conditionsLiaw, T. M.; Huang, M. C.; Luo, Y. P.; Lin, S. C.; Chou, Y. L.; Deng, Y. (American Physical Society, 2008-01)The conventional periodic boundary conditions in two dimensions are extended to general boundary conditions, prescribed by primitive vector pairs that may not coincide with the coordinate axes. This extension is shown to be unambiguously specified by the twisting scheme. Equivalent relations between different twist settings are constructed explicitly. The classification of finite-size scaling functions is discussed based on the equivalent relations. A self-similar pattern for distinct classes of finite-size scaling functions is shown to appear on the plane that parametrizes the toroidal geometry.