CAREER: Spin Polarization Spectroscopy of Complex Magnetic Materials and Spin Electronic Devices

职业：复杂磁性材料和自旋电子器件的自旋偏振光谱

• 批准号: 0239058
• 负责人: Boris Nadgorny
• 金额: $ 40万
• 依托单位: Wayne State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-01 至 2009-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0239058&HistoricalAwards=false
• 关键词: CAREER; Spin; Polarization; Spectroscopy; Complex

The possibility of exploiting the spin of electrons (or holes) in electronic devices has led to the emergence of the new field of spintronics. The efficiency of spintronics devices is strongly dependent on the degree of the spin polarization in a ferromagnet. In particular, half-metals, which are 100% spin-polarized, are of fundamental importance for the next-generation of electronic devices. The experimental confirmation of the existence of such highly spin-polarized materials systems is vital to spintronics. The proposed research focuses on developing a fundamental understanding of the basics of spin transport in highly spin-polarized materials and on the ongoing search for novel highly spin-polarized materials.We propose a cohesive research program to further develop and expand Point Contact Andreev Reflection (PCAR) Spectroscopy and to apply it to the spin polarization measurements in dilute magnetic semiconductors and metal alloys. In addition, we propose to explore the viability of a new nonvolatile ferromagnet-superconductor device based on Andreev reflection. The proposal also includes an initial exploratory study of spatially resolved spin polarization measurements (Spin Mapping) with potential in situ capabilities.The PI has recently observed for the first time Andreev reflection in the point contact geometry in a non-magnetic semiconductor, and has obtained some preliminary results in magnetic semiconductors. These results strongly indicate that the PCAR technique can become a viable measurement technique for dilute magnetic semiconductors, which is crucial for the future development of this field. In addition to the spin polarization measurements, transport, magnetic, chemical, and structural analysis will be performed to study in detail the following materials systems: 1) Dilute magnetic and non-magnetic semiconductors: Non-magnetic semiconductors (e.g., BeGaAs). Magnetic semiconductors: GaMnSb, GaMnAs, InMnSb, and MnAs.2)Other theoretically predicted half-metals: double perovskites (Sr2FeMoO6,) and CoxFe1-xS2.As part of the broader impact of his research proposal the PI is planning to promote collaboration with the local industry (especially Delphi Automotive) and with HYPRES (on ferromagnet/superconductor nonvolatile device). He is also collaborating with Oak Ridge National Laboratory, where the PI is one of the "University Champions" of the new Nanophase Materials Science Center. The spatially resolved spin polarization measurements (Spin Mapping) and will be investigated in partnership with the Center.The PI is actively involved in a comprehensive program to broaden participation of minorities in physics. He gives public lectures to high school students to explain what is involved in being a physicist and to try to eliminate a psychological barrier that often prevents many minority students and women from becoming a scientist. He is advising the Detroit Science Center on the content and scientific quality of their physics-related exhibits. The PI's two major educational goals, integrated with his research, are:1)Develop a pilot program aimed at introducing a Senior Research Project at WSU as a required part of the curriculum.2)Develop a new graduate level course "Magnetism, Magnetic Devices and Nanotechnology". This course will introduce the basic concepts in magnetism, GMR and TMR devices and sensors, novel magnetic materials, spin transport and spin polarization measurements, and modern nanofabrication techniques.

在电子器件中利用电子（或空穴）自旋的可能性导致了自旋电子学新领域的出现。自旋电子器件的效率很大程度上取决于铁磁体中自旋极化的程度。特别是 100% 自旋极化的半金属对于下一代电子器件至关重要。实验证实这种高度自旋极化材料系统的存在对于自旋电子学至关重要。拟议的研究重点是对高自旋极化材料中自旋输运的基础知识有一个基本的了解，并不断寻找新颖的高自旋极化材料。我们提出了一个内聚研究计划，以进一步开发和扩展点接触安德烈夫反射（PCAR）光谱，并将其应用于稀磁半导体和金属合金中的自旋极化测量。此外，我们建议探索基于安德烈夫反射的新型非易失性铁磁体超导体器件的可行性。该提案还包括对具有潜在原位能力的空间分辨自旋极化测量（Spin Mapping）进行初步探索性研究。PI最近首次观察到非磁性半导体中点接触几何结构中的安德烈夫反射，并在磁性半导体中获得了一些初步结果。这些结果有力地表明，PCAR技术可以成为稀磁半导体的可行测量技术，这对于该领域的未来发展至关重要。除了自旋极化测量之外，还将进行输运、磁性、化学和结构分析，以详细研究以下材料系统：1）稀磁性和非磁性半导体：非磁性半导体（例如 BeGaAs）。磁性半导体：GaMnSb、GaMnAs、InMnSb 和 MnAs。2) 其他理论上预测的半金属：双钙钛矿 (Sr2FeMoO6) 和 CoxFe1-xS2。作为其研究提案更广泛影响的一部分，PI 计划促进与当地行业（特别是德尔福汽车）和 HYPRES（关于 铁磁体/超导非易失性器件）。他还与橡树岭国家实验室合作，该实验室的 PI 是新纳米相材料科学中心的“大学冠军”之一。空间分辨自旋极化测量（自旋映射）将与该中心合作进行研究。PI 积极参与一项综合计划，以扩大少数群体对物理学的参与。他向高中生进行公开讲座，解释成为一名物理学家的过程，并试图消除经常阻碍许多少数族裔学生和女性成为科学家的心理障碍。他正在为底特律科学中心物理相关展品的内容和科学质量提供建议。 PI 的两个主要教育目标与其研究相结合，是：1）开发一个试点项目，旨在将高级研究项目引入 WSU，作为课程的必修部分。2）开发一门新的研究生课程“磁学、磁性器件和纳米技术”。本课程将介绍磁性、GMR 和 TMR 器件和传感器、新型磁性材料、自旋输运和自旋极化测量以及现代纳米制造技术的基本概念。