STUDY OF RARE-EARTH ALLOYS BY X-RAY MAGNETIC BRAGG SCATTERING

本研究的目的是发展实用的X射线磁布拉格散射和磁EXAFS测量方法，并将其应用于铁和稀土合金的研究。主要研究结果如下：1. X射线探测器和高速计数系统的研制在目前的测量中，由于必须精确地探测到10^量级的差异，所以必须在几分钟内累积10 ^8<-4>以上的计数。因此，高速计数系统能否正常工作就成为关键。我们成功地构建了由雪崩二极管X射线探测器和自制计数系统组成的系统，达到了预期的性能要求. X射线磁布拉格散射的测量测量X射线磁布拉格散射，估计了Fe的X射线磁形状因子。计算结果与谱带计算结果吻合较好.磁性EXAFS和X射线磁性圆二色性（MCD）测量测量了Fe和DyFe_2样品的磁性EXAFS谱。结果表明，这种测量提供了反映样品磁结构的有用信息，并测量了3d过渡金属和3d过渡金属与稀土金属合金的MCD分布。测量给出了有用的知识之间的关系的MCD配置文件和磁性电子的能带结构。

The objective of the present study is to develop practical methods of the measurements of X-ray magnetic Bragg scattering and Magnetic EXAFS and to apply them to the study of iron and rare-earth alloys. The results are summarized as follows :1. Construction of an X-ray detector and a high rate counting systemIn the present measurement, more than 10^8counts have to be accumulated in a few minutes, because the difference of the order of 10^<-4> must be detected precisely. Then it is the key point whether the high rate counting system works satisfactory or not. We have successfully constructed the system that meets the required performance, which composed of an avalanche-diode X-ray detector and a home made counting system.2. a measurement of X-ray magnetic Bragg scatteringMeasuring X-ray magnetic Bragg scattering, the X-ray magnetic form factor for Fe has been estimated. The values are in good accordance with those of the results of the band calcuration.3. measurements of magnetic EXAFS and X-ray magnetic circular dichroism (MCD)The profiles of magnetic EXAFS were measured for Fe and DyFe_2 samples. The rasults revealed that this measurement gives very useful informations reflecting the magnetic structure of the sample.The MCD profiles were also measured for 3d transition metals and the alloys of 3d transition metals and rare-earth metals. The measurements gave useful knowledge concerning the relation between an MCD profile and the band structure of magnetic electrons.