Magnetic-size effects in ultrathin layers

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Data

1993-08-01

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Editor

Elsevier B.V.

Resumo

We study N-layer samples (N ≤ 10) for the Heisenberg model, with ferro- and antiferromagnetic exchange couplings, using a modified version of the Onsager reaction field approximation. The present scheme includes short-range spin-spin correlations, and allows for layer-dependent order parameters when free surface boundary conditions are imposed. The limits N = 1 (two dimensions) and N → ∞ (three dimensions) can be solved analytically, while systems with several layers have to be numerically calculated. We found no indication of a phase transition at finite temperature up to the sizes investigated (N = 10), the layered systems behaving essentially as two-dimensional. A phase transition is only obtained for the three-dimensional limit. © 1993.

Descrição

Palavras-chave

Antiferromagnetism, Correlation methods, Ferromagnetism, Magnetic couplings, Phase transitions, Temperature, Three dimensional, Heisenberg model, Layer dependent order parameters, Magnetic size effects, Onsager reaction field approximation, Spin-spin correlation, Ultrathin layer, Magnetic thin films

Como citar

Journal of Magnetism and Magnetic Materials, v. 125, n. 3, p. 335-344, 1993.