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Artificial fabrication and magnetic properties of non-equilibrium ordered alloys by monatomic layr control

单原子层控制非平衡有序合金的人工制造及其磁性能

基本信息

批准号：
08455316
负责人：
TAKANASHI Koki
金额：
$ 5.63万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

项目摘要

We have compared structural and magnetic properties of the Ll_0-type FeAu ordered alloy fabricated by monatomic layr control to those of Fe (x ML) /Au (x ML) superlattices, where ML represents monatomic layr thickness. X-ray diffraction peaks corresponding to the superlattice period of x+x=2x ML have been observed definitely both for x=integers and non-integers. The X-ray diffraction patterns can be simulated by the model assuming a complete layr-by-layr growth with strucutural coherence throughout the sample, indicating the formation of coherent layred structure. The perpendicular magnetic anisotropy energy has been estimated from the in-plane and perpendicular magnetization curves. The product of the perpendicular anisotropy energy K_* and the Fe layr thickness t_<Fe>, K_*・t_<Fe>, for x=integers, decreases linearly with increasing t_<Fe> as seen in many magnetic superlattices. The interface anisotorpy energy K_s evaluated from the linear relationship increases with x for 1<less than … More or equal>x<less than or equal>3, and saturates for x<greater than or equal>4, which is explained by an extended Neel model. For x=non-integers, on the other hand, K_*・t_<Fe> vs.t_<Fe> deviates from the linear relationship, and shows oscillatory behavior with a period of 1 ML.We consider that this is a consequence associated with the reduction in K_s due to the interface roughness for x=non-integers. This study provides the first discovery of the oscillatory perpendicular anisotropy in magnetic superlattices. Furthermore, FMR measurements have indicated that the in-plane fourfold anisotropy also oscillates as a function of t_<Fe> with a period of 1.ML.In order to elucidate the origin for the oscillatory magnetic anisotropies, more precise structure analyzes including high resolution TEM,EXAFS and in situ STM are necessary. Magnetooptical measurements also indicate the oscillation of the Kerr rotation for the photon energy less than 2.5 eV.For 1<less than or equal>x<less than or equal>8, in addition, prominent structure around 3-4 eV has been observed, suggesting the formation of quantum well states of 3d electrons in Fe layrs. Less

我们比较了通过单原子层控制制备的Ll_0型Fe Au有序合金与Fe（x ML）/Au（x ML）超晶格（ML代表单原子层厚度）的结构和磁性。在x=整数和非整数的情况下，都观察到对应于x+x= 2xML的超晶格周期的X射线衍射峰。X射线衍射图可以通过假设整个样品具有结构相干性的完整的逐层生长的模型来模拟，表明相干层状结构的形成。垂直磁各向异性能量已估计从面内和垂直磁化曲线。垂直各向异性能K_* 与Fe层厚度t_的<Fe>乘积K_*·t_<Fe>（x=整数）随t_的增大而线性减小<Fe>。由线性关系求得的界面各向异性能K_s随x的增大而增大，其中1 ...更多信息或等于>x <less than or equal>3，并在x 4时饱和<greater than or equal>，这可以用扩展的Neel模型来解释。而当x=非整数时，K_*·t_<Fe>vs.t_<Fe>偏离线性关系，表现出周期为1 ML的振荡行为，我们认为这是由于x=非整数时界面粗糙度使K_s减小的结果。本研究首次发现了磁超晶格中的振荡垂直各向异性。此外，FMR测量还表明，面内四重各向异性也是以1.ML为周期振荡<Fe>的。为了阐明振荡磁各向异性的起源，需要更精确的结构分析，包括高分辨率TEM、EXAFS和原位STM。磁光测量也表明，当光子能量小于2.5eV时，克尔旋转发生振荡<less than or equal><less than or equal>。此外，在1 × 8的Fe层中，还观察到了3-4 eV附近的显著结构，表明在Fe层中形成了3d电子的量子阱态。少