Thermodynamic fluctuations in two-dimensional degenerate antiferromagnetic structures |
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Authors: | V M Rozenbaum |
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Institution: | (1) Institute of Surface Chemistry, Ukrainian National Academy of Sciences, 252022 Kiev, Ukraine |
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Abstract: | A model of a two-dimensional antiferromagnet with an arbitrary anisotropic interaction that allows for degeneracy of the ground
state is proposed. The lifting of degeneracy by thermodynamic fluctuations and the accompanying effects are studied by a method
of self-consistent calculations of Gaussian angular fluctuations that is asymptotically exact at low temperatures. Fluctuations
are shown to lead to collinear ordering of the orientations of magnetic sublattices, an effect that initiates long-range orientational
order in systems with anisotropic interaction but retains only short-range order in systems with isotropic short-range interaction.
The temperature patterns of the orientational correlators are given for the particular cases of dipole and isotropic short-range
interaction models. The nature of the Ising-like behavior of the system is discussed for the case of a strong anisotropy of
the correlators, which corresponds to quasi-one-dimensional behavior.
Zh. éksp. Teor. Fiz. 111, 669–680 (February 1997) |
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Keywords: | |
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