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Transition from Superparamagnetism to Ferromagnetic Single-Domain in a Heisenberg Model for Nano-cluster Magnetic System |
| SHAO Yuan-Zhi;HE Zhen-Hui |
| Department of Physics, Zhongshan University, Guangzhou 510275 |
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| Cite this article: |
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SHAO Yuan-Zhi, HE Zhen-Hui 2000 Chin. Phys. Lett. 17 367-369 |
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Abstract By considering a magnetic system of an ensemble of nanometer clusters without any external magnetic field, the Monte Carlo simulation of the Heisenberg model is used to investigate the transition from a superparamagnetism to a ferromagnetic single-domain state, which is caused by the growth of the clusters. We studied the variation of the dynamic growth exponent P and the transition critical size of the cluster Nc against the reduced temperature t and the uniaxial anisotropy constant A. We found that the growth exponent maximized at a certain temperature, other than being taken as a universal constant as some researchers suggested previously.
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| Keywords:
75.50.Kj
75.40.Mg
75.10.J
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Published: 01 May 2000
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