基于Heisenberg模型,利用Monte Carlo方法研究准一维有机铁磁体在不同温度,不同外磁场下的磁学性质。结果显示:自由基与主链间的反铁磁相互作用越强,相变温度越高;二聚化则削弱系统的磁性;而自由基之间的耦合增强系统的铁磁性,并提高居里温度;磁化强度曲线在低温下表现出1/3磁化强度平台,并以三个临界磁场为特征。
The magnetic properties of a quasi-one-dimensional organic ferromagnet at different temperatures and in different applied magnetic fields have been investigated by means of the Heisenberg model combined with the Monte Carlo method.The results indicate that the stronger the antiferromagnetic interactions between the side-free radicals and the sites on the main chain,the higher the transition phase temperature.Moreover,the dimerization suppresses the magnetization of the system.However,the ferromagnetic couplings between the side-free radicals enhance the ferromagnetism of the system and increase the Curie temperature.At low temperature,the magnetization curve appears a 1/3 plateau,which behaves as three critical magnetic fields.