Surface and Thin Film Magnetization of Isotropic and Anisotropic Heisenberg Ferromagnet at Low Temperatures |
| P. Modrak Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland |
| Received: January 26, 1998 |
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| The independent random walk method (which is equivalent to the noninteracting spin wave method) with no further approximations was used to calculate the low temperature expansion of: (i) the local mean spin values of an isotropic Heisenberg ferromagnet for semi-infinite crystal and (ii) the spontaneous magnetization of an anisotropic Heisenberg ferromagnet for monolayer and double layer. The full low temperature expansion starting with T3/2 term was obtained for the semi-infinite Heisenberg ferromagnet and it was shown that the spontaneous magnetization for thin films of anisotropic Heisenberg ferromagnets can exhibit a quasi-linear behaviour in certain temperature region related to the magnitude of the anisotropy. |
| DOI: 10.12693/APhysPolA.93.785 PACS numbers: 75.70.Ak, 75.30.Pd |