Three peer-approved experiments at SPring-8: spin transitions in LaCoO3; magnetism in DyCo2; ferromagnetism and superconductivity at oxide interfaces

磁性在许多材料的性质中起着引人入胜的作用。除了能够创造一个可以观察或使用的外部磁场外，磁性还可以决定材料本身的其他特性。本项目将进行的两个实验特别关注这个问题。第三个实验将研究材料的温度相关电子特性如何引起其磁性的变化。在第一个实验中，我们将研究一种多层材料，由交替超导层和磁层组成。这个实验将展示磁性在与超导性相互作用时是如何变化的。这项研究的结果将提高我们对这些现象所涉及的相互作用的理解。第二个实验的目的是研究所谓的因瓦尔效应，即在一定温度范围内，材料受热时不会膨胀。这只发生在少数材料中，并且被认为是由磁性和材料晶格之间的相互作用引起的。要研究的材料包含两种磁性，实验将使我们能够分离出它们对磁性的贡献。在最后的实验中，我们将研究材料中磁性的温度依赖性，其中电子性质的变化被认为是驱动磁性变化的原因。我们的实验将对材料的变化很敏感，因此将揭示潜在的物理原理。为了提供所需的灵敏度，这些实验都要求我们使用x射线来测量磁性质的具体细节。获得足够强度和特定性质的x射线的唯一方法是使用同步加速器源。世界上有一些这样的工具。这些实验中同步加速器的选择是基于日本SPring-8的特定实验设施和样品环境。

Magnetism plays a fascinating role in the properties of many materials. As well as being able to create an external magnetic field that can be observed or used, magnetism can determine other properties of the material itself. Two of the experiments that will be performed in this project, in particular, are focussed on this issue. The third experiment will study how the temperature dependent electronic properties of a material cause changes in its magnetic properties. In the first experiment, we will study a multilayered material, consisting of alternating superconducting and magnetic layers. The experiment will show how the magnetism changes as it interacts with the superconductivity. The results of the study will improve our understanding of the interactions involved in these phenomena. The objective of the second experiment is to study the so-called Invar effect, where, over a certain temperature range, a material does not expand as it is heated. This only occurs in a few materials, and is considered to arise from an interaction between the magnetic properties and the lattice of the material. The material to be studied contains two magnetic species, and the experiment will enable us to separate their contributions to the magnetic properties. In the final experiment, we will study the temperature dependence of the magnetism in a material where changes in the electronic properties are thought to drive changes in the magnetism. Our experiment will be sensitive to the changes in the material and will hence reveal the underlying physics.In order to provide the sensitivities required, these experiments all require us to use x-rays to measure specific details of the magnetic properties. The only way to obtain x-rays of sufficient intensity and with the particular properities required, is to use a synchrotron source. There are a few of these available world-wide. The choice of synchrotron for these experiments was based on the particular experimental facilities and sample environment available at the SPring-8 in Japan.