Computer simulation of surface phase transitions in semi-infinite Ising magnets

Белим, С. В.; Koval, T. A.

doi:10.1134/s1027451015040047

Cited by 2 publications

(1 citation statement)

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“…The phase diagram here corresponds to the one predicted by the phenomenological theory. The possibility of the state where the bulk temperature is higher than the surface one for the ferromagnetic Ising model was demonstrated by computer modeling in the papers [17,18]. Here, a surface-disordered bulk-ordered phase (SD / BO) is observed in the phase diagram of the substance.…”

Section: Introductionmentioning

confidence: 97%

Study of the critical behavior of antiferromagnetic thin films by computer modeling

Белим¹,

Trushnikova²

2018

LoM

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In this paper, the surface phase transitions in thin films described by the antiferromagnetic Ising model are studied by computer modeling. The Metropolis algorithm is used. Modeling is performed at various values of the ratio between the exchange integrals on the surface and in the bulk of the system, R S. The difference of the exchange integral of the interaction between the surface spins and the first subsurface layer, R SB , from the bulk value is also taken into account. The limiting cases of the R SB value are considered. Two order parameters are used. The first order parameter determines the antiferromagnetic order in the bulk of a system. It is calculated as the staggered magnetization of the spins located not on the surface. Its value is equal to the difference between the magnetic moments for two sublattices. For the study of the surface phase transition, the second order parameter is introduced. It is calculated as the staggered magnetization of the spins located on the free surface. In order to find the phase transition temperature, the bulk and surface Binder's cumulants are used. A computer experiment is performed for different values of film thickness ranging from 4 to 12 layers. The ratio between the exchange integrals varies from 0.5 to 2.0. It is shown that the temperatures of the bulk and surface phase transitions are identical at all the ratios between the exchange integrals. The transition temperature grows with increasing ratio between the exchange integrals, R S. The growth rate of the transition temperature depends on the thickness of a film and the R SB value. The difference of the exchange integral of the interaction between the surface layer and the first subsurface layer leads to more rapid growth of the transition temperature. For all the values of exchange integrals there is an intersection point of temperature curves for any thickness of a film.

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Section: Introductionmentioning

confidence: 97%