Constant Coupling Approximations to Anisotropic Heisenberg Model
| Autor: | Matayoshi, Seitaro, Shinjo, Tsuneo |
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| Jazyk: | japonština |
| Rok vydání: | 1979 |
| Předmět: | |
| Zdroj: | 琉球大学理工学部紀要. 理学編 = Bulletin of Science & Engineering Division, University of Ryukyus. Mathematics & natural sciences. 27:19-38 |
| Popis: | The Curie points T_c (μ) as the function of anisotropic interaction parameter μ are calculated by both the constant coupling and the improved constant coupling approximations. T_c (μ) by these approximations decrease, as the parameter μ increases, with similar tendencies on the whole. Especially in two dimensional system, the Curie points become T_c = 0 and dT_c/dμ= infinity at μ= 1. The short range orders are investigated to understand the physical meaning of the sudden change in the neighbourhood of μ= 1. The effect of the second neighbour anisotropic exchange interaction on the curie point is studied by two approximations mentioned above. It is obtained that the occurrence of the order in this anisotropic system is enhanced if the second neighbour exchange interaction parameter is ferromagnetic, and is suppressed if antiferromagnetic, as in the isotropic system. The Curie points calculated by these two approximations are in contradiction to the rigorous theory in the isotropic low dimensional systems. Discussions are given how to overcome the faults In these approximate methods. It is carried out to extend the theorem due to Mermin and Wagner into the anisotropic Heisenberg model with finite range interactions. 紀要論文 |
| Databáze: | OpenAIRE |
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