磁性金属材料中交换耦合作用和自旋波的研究  

Research of spin wave function and exchange coupling interactions in metal magnetic materials

作　　者：郑勇林[1,2] 卢孟春[2] 郭红霞[1] 包秀丽[2] 

机构地区：[1]成都大学电子信息工程学院,成都610106 [2]长江师范学院凝聚态物理研究所,重庆408100

出　　处：《物理学报》2015年第17期301-306,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11205022);重庆市教委科学技术研究项目(批准号:KJ061305;KJ081307)资助的课题~~

摘　　要：基于交换耦合理论通常使用的近似分析的一般原理,严格的分析了没有特定假设情况下的磁序范围或有关磁化密度的形式,及在任何近似下提出一种关于耦合参数的计算方法.并结合铁磁系统(磁性金属材料Gd,Fe,Ni),定量的讨论了这种关系的适用范围,也对自旋波和交换耦合进行了相关分析.分析表明:对于近邻磁性原子之间的交换耦合的计算以及在有限波矢量情况下对自旋波谱的计算都得到较为有意义的改进.提出的交换耦合近似及自旋波谱的关系,应用于铁磁系统时对近邻原子之间相互作用能给出较好的描述,或对任何磁体中非完全局域磁化的自旋波谱较大波矢部分给出较合理的描述.从磁性理论来看,按照本文模型应用于磁学系统计算得到的结果与实验结果较好的符合.Exchange coupling is one of the most important fundamental interactions in ferromagnetic systems. Understanding of the parameters in this interaction may help describe numerous properties of metal magnetic materials. However, in the localized electron theory or itinerant electron theory there are also certain difficulties when utilizing this approximation method to study magnetic ordering problems for multi-atom systems. In realistic magnets exchange coupling is also related to the coexistence of localized and itinerant degrees of freedom. In this case Heisenberg exchange relationship has some limitations. If the exchange relationship only depends on the structure of the magnet, and is not related to energy differences between the phases, we can better avoid the Heisenberg exchange limits. Based on this, we use the general principle of the exchange coupling theory to analyse the usual approximation, and discuss the opportunity to calculate the parameters of such coupling rigorously without specific assumptions about the range of magnetic order or any approximation about the form of magnetization density. We propose a method for calculating the exchange coupling parameter to any approximation. The range of applicability of the above relation is discussed quantitatively for real magnetic systems （magnetic metal materials Gd, Fe, Ni） and spin waves, and the relevance for the exchange coupling is also analysed. This analysis for metal magnetic system （Fe, Ni and Gd） shows that the most significant improvement is obtained for exchange coupling between nearest magnetic atoms and for spin wave spectrum at finite wave vectors. It can be described by the relationship between the exchange coupling approximation and spin wave spectrum, and also interaction between the nearest neighbor magnetic atoms in ferromagnetic systems;these will give reasonable description to the large wave vectors part of spin wave spectra in any magnet with not fully localized magnetism. This point of view from the magnetism theory is consis

关 键 词：磁性金属材料 交换耦合作用 自旋波函数 FE NI 

分 类 号：O469[理学—凝聚态物理]