Neutron Scattering Studies of New Magnetic Semiconductors and their Epitaxial Structures

*非技术摘要*磁性半导体(MSS)由于其在自旋电子学中的潜在应用而继续成为活跃研究的主题，自旋电子学是一种可能对未来的通信和计算机技术产生重大影响的新型电子学。自然产生的MS对实际的自旋电子学没有用处，因为它们只在非常低的温度下保持其磁性。因此，目前大量的努力集中在创造具有合适性能的新的人造MS上。最近已经合成了几个这样的系统，很好地了解它们的磁性是一项相当重要的任务。中子散射是研究磁性固体的有力工具。这个项目的目的是利用中子散射技术的独特能力来研究这些新的MS中当前感兴趣的一系列影响。非弹性中子散射将被用来在微观水平上清楚地了解这些材料中磁性原子之间的相互作用。一些新的MSS合金只能以超薄膜的形式制备。特别适合于研究薄膜磁性的中子反射测量技术将被用于研究这种超薄的MS层和夹在MS层之间的其他材料的多层膜。该项目涉及与来自美国和其他国家的几个研究小组的合作。两名研究生将参与这项研究，并将鼓励本科生参与该项目。*技术摘要*该项目的目标是利用弹性和非弹性中子散射技术的独特能力，研究最近合成的新型磁性半导体中电流感兴趣的一系列影响。由于它们在自旋控制电子学(自旋电子学)中的潜在应用，这些材料现在受到了强烈的关注。特别是，非弹性散射将被用来研究被广泛研究的“典型”自旋电子学材料Ga1-xMnxAs中的自旋波传播，以及在常压和高达8kbar的高压下，表征稀释态合金中孤立的Mn-Mn和Co-Co对的磁激发。这些实验的结果有望提供许多关于这些系统中磁交换相互作用的新的微观层面的信息。该项目的另一个重要部分是基于Ga1-xMnxAs和Ge1-x-yMnxCoy的薄膜和超晶格结构的中子反射仪研究。这些测量将集中在研究这种外延系统中的层间耦合效应和磁畴。该项目涉及与来自美国和其他国家的几个合作伙伴的合作。两名研究生将参与这项研究。此外，还将鼓励本科生参与，并为有抱负的年轻科学家提供有吸引力的机会。

*** NON-TECHNICAL ABSTRACT ***Magnetic semiconductors (MSs) continue to be the subject of vigorous research because of their potential application in "spintronics", a novel electronics that may have a great impact on future communication and computer technologies. Naturally occurring MSs are not useful for practical spintronics since they retain their magnetism only at very low temperatures. Therefore, substantial efforts are currently focused on creating new man-made MSs of suitable properties. Several such systems have recently been synthesized, and good understanding of their magnetism is a task of considerable importance. Neutron scattering is a powerful tool for investigating magnetic solids. The objective of this project is to exploit the unique capabilities of neutron scattering techniques for investigating a range of effects of current interest in these novel MSs. Inelastic neutron scattering will be used for obtaining a clear microscopic-level insight into interactions between magnetic atoms in these materials. Some new MSs alloys can be prepared only in the form of ultra-thin films. The technique of neutron reflectometry, which is particularly well suited for investigating thin film magnetism, will be used for studying such utltra-thin MS layers and multilayers containing other materials sandwiched between MS layers. The project involves collaboration with several research groups from the US and other countries. Two graduate students will take part in the research, and the participation of undergraduate students in the project will be encouraged.*** TECHNICAL ABSTRACT ***The objective of this project is to exploit the unique capabilities of elastic and inelastic neutron scattering techniques for investigating a range of effects of current interest in recently synthesized novel magnetic semiconductors. These materials now receive strong attention because of their potential application in spin-controlled electronics ("spintronics"). In particular, inelastic scattering will be used for investigating propagating spin waves in Ga1-xMnxAs, an extensively studied "prototypical" spintronics material, as well for characterizing the magnetic excitations of isolated Mn-Mn and Co-Co pairs in diluted alloys of Zn1-xMnxO, Zn1-xCoxO and several other materials derived from II-VI semiconductors at ambient pressure and high pressures up to 8 kbar. The results of such experiments are expected to provide much new microscopic-level information about magnetic exchange interactions in these systems. Another substantial part of the project is neutron reflectometry studies of thin film and superlattice structures based on Ga1-xMnxAs and Ge1-x-y MnxCoy. The measurements will be focused on investigating interlayer coupling effects and magnetic domains in such epitaxial systems. The project involves collaboration with several partners from the US and other countries. Two graduate students will participate in the research. Also, participation of undergraduate students will be encouraged and attractive opportunities will be offered to those aspiring young scientists.