Neutron and Synchrotron Radiation Scattering Studies of Multilayered Structures Based on Europium Chalcogenides and other Magnetic Semiconductors

本研究的目的是利用中子衍射、中子反射率和同步辐射反射率来研究含磁性/非磁性半导体组成的新型超晶格的磁性和结构特性。人工磁性异质结构和多层材料的研究大多集中在金属体系上；低载流子浓度体系的实验和理论结果直到最近才开始出现。这类系统的研究具有根本性的重要性，因为其磁性的相互作用机制不同于金属。此外，由绝缘或半导体化合物组成的异质结构和多层结构也很有趣，因为许多这些材料都是反铁磁体，通常具有层状结构，因此为“工程”超晶格提供了机会。待研究的系统将主要基于铕和锰硫属化合物，样品由奥地利林茨约翰内斯·开普勒大学的分子束外延制备。中子散射研究将主要在国家科学技术研究所进行，x射线测量将在布鲁克海文国家实验室进行。磁特性的补充测量将在麻省理工学院进行。这项研究的目的是利用中子散射和同步加速器x辐射技术来研究由磁性和非磁性半导体材料构建的多层原子“超晶格”的磁性和结构特性。对这类系统的研究具有根本性的重要性，因为一个磁性层中的原子通过中间的非磁性层与另一个磁性层中的原子相互作用（即通信）的物理机制知之甚少，并且与应用于金属多层超晶格的机制有很大不同。要研究的材料将主要基于磁性硒化铕和锰以及非磁性硒化铅和碲。这是一个多学科项目，样品在奥地利林茨的约翰内斯·开普勒大学准备，实验工作在国家标准与技术研究所和布鲁克海文国家实验室进行。此外，将在麻省理工学院对磁性进行补充测量。* * *

9510434 Giebultowicz The objective of the proposed research is to use neutron diffraction, neutron reflectivity, and synchrotron radiation reflectivity for investigating magnetic and structural properties of novel superlattices composed of mangetic/non-magnetic semiconductors. Most research on artificial magnetic heterostructures and multilayers has been done on metallic systems; experimental and theoretical results for low carrier concentration systems have only recently begun emerging. Studies of such systems are of fundamental importance because the interaction mechanisms underlying their magnetic properties differ from those of metals. Also, heterostructures and multilayers composed of insulating or semiconducting compounds are interesting in that many of these materials are antiferromagnets, frequently having layered structures, thus offering opportunities for "engineering" the superlattices. Systems to be studied will be based primarily on europium and manganese chalcogenides, with samples prepared by molecular beam epitaxy at the Johannes Kepler University, Linz, Austria. Neutron scattering studies will be conducted primarily at the National Institute of Science and Technology, and X-ray measurements at Brookhaven National Laboratory. Complementary measurements of magnetic properties will be made at the Massachusetts Institute of Technology. %%% The objective of the proposed research is to use neutron scattering and synchrotron X-radiation techniques to investigate the magnetic and structural properties of multilayer atomic "superlattices" built up from magnetic and non-magnetic semiconducting materials. Studies of such systems are of fundamental importance because the physical mechanisms by which the atoms in one magnetic layer interact (i.e., communicate) with those in another magnetic layer through an intervening non-magneti c layer are poorly understood and differ significantly from the mechanisms which apply in the case of metallic multilayer superlattices. The materials to be investigated will be based primarily on magnetic europium and manganese selenides and tellurides and non-magnetic lead selenide and telluride. This is a multidisciplinary project, with samples being prepared at the Johannes Kepler University, Linz, Austria, and experimental work carried out at the National Institute of Standards and Technology and at the Brookhaven National Laboratory. In addition, complementary measurements of the magnetic properties will be made at the Massachusetts Institute of Technology. ***