Magnetic Semiconductor Solid Solutions

非技术描述：本项目的目标是合成Eu（S，Se）和（Eu，Sm）Se型材料。 主体材料EuSe是一种特殊的半导体，它可以在高磁场下表现出一种类型的磁性（铁磁性），在低磁场下表现出第二种类型的磁性（反铁磁性）。 在第一个系统中，硫的掺入，应该从反铁磁到铁磁，这将允许电子结构和磁有序之间的关系的研究，以了解磁制冷（磁热效应）背后的机制。在第二个系统中，钐取代铕将能够理解稀土元素的电子结构和电荷之间的关系。该研究将针对这些材料的散装和纳米颗粒，提供形态和大小对磁性和电子性质的作用的协同理解。技术说明：该项目涉及镧系单硫族元素的本体和纳米颗粒的合成，这些材料具有内在的半导体性和磁性。 将研究Eu（S，Se）的阴离子固溶体的作用，以确定阴离子对电子结构的改变的后果以及这如何改变磁热效应。 此外，磁性圆二色性将被用来探测这些合金的激发态。 第二个项目涉及探测镧系元素在（Eu，Sm）Se固溶体中的作用，以了解镧系元素氧化态作为电子结构的函数。 虽然EuSe已被发现含有二价铕和SmSe具有二价钐，低掺杂水平的钐注入三价态的钐。 这些变化将通过使用L边X射线吸收光谱进行研究。

NON-TECHNICAL DESCRIPTION: The goal of this project is to synthesize materials of the type Eu(S,Se) and (Eu, Sm)Se. The host material, EuSe is a special semiconductor that can exhibit one type of magnetism (ferromagnetism) under high magnetic fields and a second type (antiferromagnetism) at low fields. In the first system, incorporation of sulfur, should shift the magnetic ordering from antiferro- to ferromagnetic, which will allow a study of the relationship between the electronic structure and magnetic ordering in order to understand the mechanism behind magnetic refrigeration (magnetocaloric effect). In the second system, substitution of samarium for europium will enable the understanding of the relationship between the electronic structure and the charge on the rare earth element. The research will target these materials in both the bulk and as nanoparticles, providing a synergistic understanding of the role of morphology and size on the magnetic and electronic properties. TECHNICAL DESCRIPTION: The project involves the synthesis of both bulk and nanoparticles of lanthanide monochalcogenides, which are intrinsically semiconducting and magnetic. The role of anion solid solutions of Eu(S,Se) will be investigated to determine the consequences of the anion changes to the electronic structure and how this changes the magneto-caloric effect. In addition, magnetic circular dichroism will be used to probe the excited states of these alloys. The second project involves probing the role of the lanthanide in solid solutions of (Eu,Sm)Se, to understand the lanthanide oxidation state as a function of the electronic structure. Although EuSe has been found to contain divalent europium and SmSe has divalent samarium, low doping levels of samarium inject samarium in the trivalent state. These variations will be investigated through use of L-edge X-ray absorption spectroscopy.