论文标题
三维FE7S8化合物的相变和磁性的平均场理论和蒙特卡洛模拟
Mean field theory and Monte Carlo simulation of Phase transitions and Magnetic Properties of a tridimensional Fe7S8 Compound
论文作者
论文摘要
在AB-Initio计算，平均场近似（MFA）和Monte Carlo Simulation（MCS）的框架内，已经研究了FE7S8材料的结构，电子和磁性。我们的研究表明，具有自旋s = 2的铁原子的两种形式，而带自旋σ= 5/2的Fe3+是最可能的构型。与Fe2+和Fe3+离子之间以及Fe3+和Fe3+离子之间以及相邻层的Fe2+离子之间的抗磁性自旋偶联的混合ISIN模型，具有Fe2+和Fe3+离子之间，Fe3+和Fe3+离子之间的混合模型已用于研究该化合物的磁性。我们证明了磁相变位可以是第一阶或第二阶的中间，具体取决于交换相互作用和晶体场的值。在每个第二铁层中存在空缺导致磁矩的取消不完全取消，因此导致了铁磁性的出现。已经发现了磁化行为中的异常，并将其与实验结果进行了比较。
The structural, electronic and magnetic properties of Fe7S8 material have been studied within the framework of the ab-initio calculations, the mean field approximation (MFA) and Monte Carlo simulation (MCS). Our study shows that two forms of the iron atoms, Fe2+ with spin S=2, and Fe3+ with spin σ=5/2 are the most probable configurations. A mixed Ising model with ferromagnetic spin coupling between Fe2+ and Fe3+ ions and between Fe3+ and Fe3+ ions, and with antiferromagnetic spin coupling between Fe2+ ions of adjacent layers has been used to study the magnetic properties of this compound. We demonstrated that the magnetic phase transition can be either of the first or of the second order, depending on the value of the exchange interaction and crystal field. The presence of vacancies in every second iron layer leads to incomplete cancellation of magnetic moments, hence to the emergence of the ferrimagnetism. Anomalies in the magnetization behavior have been found and compared with the experimental results.
