Transition from Superparamagnetism to Ferromagnetic Single-Domain in a Heisenberg Model for Nano-cluster Magnetic System  

作　　者：SHAO Yuan-Zhi HE Zhen-Hui 邵元智;何振辉(Department of Physics,Zhongshan University,Guangzhou 510275)

机构地区：[1]Department of Physics,Zhongshan University,Guangzhou 510275

出　　处：《Chinese Physics Letters》2000年第5期367-369,共3页中国物理快报（英文版）

基　　金：Supported by the National Natural Science Foundation of China under the Grant No.59702004.

摘　　要：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 N_(c) against the reduced temperature t and the uniaxial anisotropy constant A.Ws found that the growth exponent maximized at a certain temperature,other than being taken as a universal constant as some researchers suggested previously.

关 键 词：HEISENBERG CLUSTER EXPONENT 

分 类 号：O41[理学—理论物理]