纳米磁性颗粒的磁相变研究

Magnetic state and phase transition of Nanoparticle

利用Monte Carlo模拟方法研究了具用相互竞争的近邻与次近邻交换耦合作用的Heisenberg体心立方晶格结构纳米颗粒的磁性质。模拟结果表明,当考虑次近邻交换作用时,系统的磁相图变得更加复杂,出现了三类不同的磁有序:铁磁序(F)、第一类反铁磁序(AF1)及第二类反铁磁序(AF2)。利用不同的序参量来表征不同的磁有序,给出了颗粒尺寸、各向异性的大小等对铁磁或反铁磁颗粒的相变行为的影响。模拟结果与实验结果一致。

Based on Monte Carlo simulation,the magnetic properties of Heisenberg body-centered cubic structure with exchange coupling of competing nearest neighbor and next-nearest neighbor are studied.Three kinds of antiferromagnetic order (AF1 and AF2) and a ferromagnetic (F) order have been predicted to exist in Magnetic phase diagram of the system..The effects of particle size and anisotropy on the magnetization and phase change behavior of ferromagnetic or antiferromagnetic particles are given.The simulation results are consistent with the experimental facts.