Neutron Scattering Studies of New Magnetic Semiconductors and their Epitaxial Structures

磁性半导体（MSs）由于其在“自旋电子学”（一种可能对未来通信和计算机技术产生重大影响的新型电子学）中的潜在应用而继续成为蓬勃研究的主题。自然产生的MSs对实际的自旋电子学没有用处，因为它们只有在非常低的温度下才能保持磁性。因此，大量的努力目前集中在创造新的人造MSs合适的性质。最近已经合成了几个这样的系统，并且很好地理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。该项目的目标是利用中子散射技术的独特能力来研究当前对这些新型ms感兴趣的一系列影响。非弹性中子散射将用于获得对这些材料中磁性原子之间相互作用的清晰微观水平的洞察。一些新的MSs合金只能以超薄膜的形式制备。特别适合研究薄膜磁性的中子反射技术将用于研究这种超薄质谱层和夹在质谱层之间的含有其他材料的多层膜。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。两名研究生将参与研究，并鼓励本科生参与项目。技术摘要本项目的目的是利用弹性和非弹性中子散射技术的独特能力来研究最近合成的新型磁性半导体中当前感兴趣的一系列效应。这些材料现在受到强烈的关注，因为它们在自旋控制电子（“自旋电子学”）中的潜在应用。特别是，非弹性散射将用于研究Ga1-xMnxAs（一种广泛研究的“原型”自旋电子学材料）中的传播自旋波，以及表征在环境压力和高达8 kbar的高压下，Zn1-xMnxO， Zn1-xCoxO和其他几种来自II-VI半导体的材料的稀释合金中孤立的Mn-Mn和Co-Co对的磁激发。这些实验的结果有望为这些系统中的磁交换相互作用提供许多新的微观信息。该项目的另一个重要部分是基于Ga1-xMnxAs和Ge1-x-y MnxCoy的薄膜和超晶格结构的中子反射研究。测量将集中于研究这种外延系统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。两名研究生将参与研究。此外，我们将鼓励本科生的参与，并为那些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.