Magnetic Structures of Metallic Multilayers by Resonant X-ray Magnetic Scattering of Circularly Polarized Synchroton X-rays

1. 利用共振x射线磁衍射（RXMD）在Gd L3吸收边测定了Fe/Gd金属多层中Gd层的磁性结构。补偿温度（约120 K）以上的磁结构与用简单的理论方法得到的结果一致。测得的M-H曲线由测定的磁结构再现。补偿温度下的磁性结构不能用简单的理论方法推导出来，说明Gd层的磁各向异性对磁性结构的影响是显著的。用RXMD在dyl3吸收边测定了Fe/Dy金属多层膜中Dy层的磁性结构。在50 ~ 300 K范围内，Dy层的磁性结构与Fe/Gd金属多层材料中Gd层的磁性结构相似。然而，Dy磁性结构的起源被认为与Gd的情况不同。它被认为是比块体Dy金属本身具有更多的新型磁相互作用。在Gd层低温至居里温度范围内，测量了Gd/Cu多层金属层在Gd L3和Cu K吸收边的x射线磁圆二色性（XMCD）光谱，以研究非磁性层中与铁磁性层恒定的磁极化的基本行为。Gd层的（5d）磁极化和Cu层的（4p）磁极化都与体磁化强度（主要是Gd 4f）成正比，与XMCD谱有关。然而，铜的比例常数取决于铜层厚度。这表明，即使Gd层磁化强度相同，随着Cu层厚度的变化，Cu层中感应的总磁矩也不同。对两种Co/Cu样品测量了Co和Cu的XMCD光谱对磁场的依赖性；一种样品（AF样品）表现出巨磁电阻效应，另一种样品（F样品）没有。在相同Co XMCD强度下，F样品中Cu层的总磁极化大于AF样品中的总磁极化。结果表明，AF样品有抑制Cu层铁磁极化的趋势。为了测量RXMD在非磁性铜层中引起的极小磁极化分布，我们正在开发一种使用高计数率检测器的新系统。我们成功地观测到了(I(+)-I(-))/(I(+)+I(-)~ 0.001的磁布拉格峰。少

1. Magnetic structures of Gd layers in Fe/Gd metallic multilayers were determined by resonant x-ray magnetic diffraction (RXMD) at the Gd L3 absorption edge. The determined magnetic structures above the compensation temperature (ca. 120 K) are consistent with those derived from a simple theoretical method. The measured M-H curves are reproduced from the determined magnetic structures. The magnetic structures below the compensation temperature cannot be derived from the simple theoretical method, indicating the significant effect of the magnetic anisotropy of the Gd layers on the magnetic structures.2. Magnetic structures of Dy layers in Fe/Dy metallic multilayers were determined by RXMD at the Dy L3 absorption edge. The magnetic structures of the Dy layers between 50 and 300 K are similar to those of the Gd layers in the twisted state of the Fe/Gd metallic multilayers. The origin of the Dy magnetic structures, however, is thought to be different from the Gd case. It is thought to be sc … More rew-type magnetic interaction that the bulk Dy metal inherently has.3. The x-ray magnetic circular dichroism (XMCD) spectra of the Gd/Cu metallic multilayers at the Gd L3 and Cu K absorption edges were measured from low temperature up to the Curie temperature of the Gd layer in order to investigate the basic behavior of the magnetic polarization induced in the nonmagnetic layers in constant with the ferromagnetic layers. Both the (5d) magnetic polarization of the Gd layers and the (4p) polarization of the Cu layers, which are relevant to the XMCD spectra, are proportional to the bulk magnetization (mainly Gd 4f). However, the proportional constant for Cu depends on the Cu layer thickness. This indicates that even if the Gd layer magnetization is the same, the total magnetic moment induced in the Cu layer is different when the Cu layer thickness changes.4. The magnetic field dependence of the Co and Cu XMCD spectra was measured for two Co/Cu samples; one (AF sample) showed the giant magnetoresistance (GMR) effect and the other (F sample) did not. The total magnetic polarization of the Cu layer in the F sample is larger than that in the AF sample if we compare them under the same Co XMCD intensities. A tendency is suggested that the AF sample suppresses the ferromagnetic polarization of the Cu layer.5. In order to measure a distribution of a very small magnetic polarization induced in the nonmagnetic Cu layer by RXMD, we are developing a new system using a high counting rate detector. We successfully observed magnetic Bragg peaks of the magnitude of (I(+)-I(-))/(I(+)+I(-)~ 0.001. Less