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

我们将单原子层控制制备的Ll_0型FeAu有序合金的结构和磁性能与Fe (x ML) /Au (x ML)超晶格的结构和磁性能进行了比较，其中ML表示对应于单原子层厚度的X射线衍射峰。对于 x=整数和非整数，都明确观察到了 x+x=2x ML 的超晶格周期 X 射线衍射图案可以通过以下方式模拟。模型假设整个样品具有结构相干性的完整逐层生长，表明形成了相干层状结构，垂直磁各向异性能量是根据面内和垂直磁化曲线估计的。 K_* 和 Fe 层厚度 t_<Fe>、K_*・t_<Fe>，对于 x=整数，随着增加而线性减小t_<Fe> 如在许多磁性超晶格中所见，从线性关系评估的界面各向异性能量 K_s 在 1<小于...大于或等于>x<小于或等于>3 时随 x 增加，并且在 x<大于时饱和。或等于>4，这是由扩展尼尔模型解释的，另一方面，对于x=非整数，K_*·t_<Fe>与t_<Fe>偏离线性关系，并且显示周期为 1 ML 的振荡行为。我们认为这是由于 x=非整数的界面粗糙度而导致 K_s 降低的结果。这项研究首次发现了磁超晶格中的振荡垂直各向异性。此外，FMR 测量表明，面内四重各向异性也会作为 t_<Fe> 的函数以 1.ML.In 的周期振荡为了阐明振荡磁各向异性的起源，需要更精确的结构嵌套，包括高分辨率 TEM、EXAFS 和原位 STM 测量，还可以表明光子能量小于 2.5 eV 时克尔旋转的振荡。对于 1<。小于或等于>x<小于或等于>8，此外，还观察到3-4 eV附近的突出结构，表明形成了3d量子阱态Fe 层中的电子较少。