磁性单层膜磁学性质的Monte Carlo模拟

Monte Carlo Simulation of Magnetic Monolayer Films

采用类Ising模型,利用Monte Carlo方法研究了磁性单层膜中退磁性偶极作用和铁磁性交换作用对系统磁学性质的影响.结果显示,随着偶极相互作用的增加,系统在低温下的磁化出现平台现象,此时磁化曲线可分为2个阶段,在低外场下,温度升高,系统易磁化,在高外场下则反之.这种新奇的磁化行为导致系统的磁熵变在低温低外场下出现大于零的反常行为.在模拟过程中,对长程力作用采用了比较精确的处理方法.

Monte Cado simulation is used to study the magnetic properties of magnetic monolayer films with an Ising-like model in which the exchange interaction and dipolar interaction are considered. The system shows an abnormal magnetization with an increasing of the dipolar interaction at low reduced temperatures. The magnetization is divided into two stages. The magnetization becomes difficult with increasing temperature in low external fields. The reverse process occurs in high external fields. This magnetization behavior results in an abnormal phenomenon that the magnetic entropy changes above zero at low temperatures in external fields. An accurate method is introduced to deal with the long-range interaction.