Diluted Magnetic Dielectrics : New Spintronics Materials and Devices

本研究旨在开发一种利用新型材料稀释磁介电体（DMD）的自旋注入技术。DMD在室温下既具有铁磁性，又具有绝缘性，后者与稀释磁性半导体（DMS）相反。这一建议将利用我们最近的观察，即在掺杂过渡金属离子的tio2或ZnO等宽带隙氧化物中，不需要载流子的存在来获得铁磁性。自旋注入将通过磁隧道势垒中的自旋滤波来实现。本研究将探讨DMD材料的基本材料和器件问题及其实际应用。DMD薄膜的磁性、结构、形态和介电性能将在自旋过滤势垒中得到优化。为此，将发现当膜厚度减小到~2纳米（估计的最佳势垒厚度）时，物理性质的标度规律。这也将为研究DMD材料的铁磁性机理提供新的思路。本研究的最终目标是通过DMD自旋滤波器隧道屏障研究自旋滤波和电自旋注入，并展示利用这些效应的原型器件结构。演示装置结构将使用溅射技术进行生长，并通过各种先进的表征和测量方法进行研究。总的来说，这项研究将通过为开发实际有用的器件提供现实的途径，为半导体自旋电子学领域的发展提供动力。将磁极化载流子有效地注入到半导体结构中，特别是在室温下，并演示一个实用的装置是目标。该提案还将对西澳大学的教学、教育和推广活动产生广泛影响。具体来说，它将直接影响PI在西澳大学教授的研究生课程（磁性材料、键合和晶体学）和本科生课程（纳米科学和纳米技术）。后者采用合作学习模式，研究生在监督下参与本科生教育。PI和他的研究小组，特别是研究生和本科生，通过每年的西澳大学工程学院开放日积极参与外展活动，来自当地学校的4000多名学生参加了开放日活动。我们去年首次开发了一个广泛的、互动的、非常受欢迎的磁性和自旋电子学展览，这将在未来几年得到完善和扩大。该项目还将包括与东京工业大学的合作，重点是研究生的培训和教育。PI还致力于提高研究生参与其研究项目的多样性；他是华盛顿大学研究生院少数民族服务机构招聘教师委员会的创始成员。华盛顿大学也有一系列广受好评的项目，以鼓励研究和教学的多样性。PI将继续积极与这些组织合作，特别是教学研究与发展中心（CIDR），工程学习与教学中心（CELT），少数民族科学与工程计划（MSEP）和科学与工程妇女（WiSE），以增加妇女和不同背景的人参与他在西华大学校园的所有教学和研究活动。

This research is directed at the development of a spin injection technique utilizing a new class of materials, diluted magnetic dielectrics (DMD). DMD are both ferromagnetic at room temperature and yet insulating, the latter in contrast with diluted magnetic semiconductors (DMS). This proposal will make use of our recent observation that the presence of carriers is not required for ferromagnetism in wide band gap oxides such as TiO2or ZnO doped with transition metal ions. Spin injection will be achieved through spin filtering in a magnetic tunnel barrier. This research will explore both fundamental material and device issues of DMD materials and their practical application. Magnetic, structural, morphological and dielectric properties of DMD thin films will be optimized in application to spin filtering barriers. For this purpose, scaling laws will be found for the physical properties with the film thickness decreasing to ~2 nanometers, an estimated optimum barrier thickness. This will also provide a new insight into the mechanisms of ferromagnetism in DMD materials. The final objective of this research is to investigate both spin filtering and electrical spin injection via DMD spin filter tunnel barriers, and to demonstrate prototype device structures using these effects. The demonstration device structures will be grown editorially using sputtering techniques and investigated by a variety of advanced characterization, and measurement methods. Broadly, this research will add momentum to the development of the field of semiconductor spin electronics by providing a realistic route for the development of practically useful devices. Effective injection of magnetically polarized current carriers into semiconductor structures, especially at room temperatures, and the demonstration of a practical device are the goals. The proposal will also have broad impact on teaching, educational and outreach activities at UW. Specifically, it will have direct bearing on both graduate (Magnetic materials, Bonding and crystallography) and undergraduate (Nanoscience and nanotechnology) courses that the PI teaches at UW. The latter is taught in a cooperative learning mode with supervised involvement of the graduate students in the education of undergraduates. The PI and his research group, especially the graduate and undergraduate students, are actively involved in outreach activities through the annual UW, College of Engineering open house that is attended by more than 4000 students from local schools. We developed an extensive, interactive and very popular exhibit on magnetism and spin-electronics for the first time last year and this will be refined and enlarged in the coming years. The project will also include collaborative work with the Tokyo Institute of Technology with emphasis on graduate student training and education. The PI is also committed to enhancing the diversity of the graduate student participation in his research program; he is a founding member of the UW Graduate School faculty committee on Recruitment from Minority Serving Institutions. The UW also has a wide range of acclaimed programs to encourage diversity in research and teaching. The PI will continue to actively work with these organizations, specifically the Center for Instructional Research and Development (CIDR), Center for Engineering Learning and Teaching (CELT), Minority Science and Engineering Program (MSEP) and Women in Science and Engineering (WiSE) to increase the participation of women and people of diverse backgrounds in all his teaching and research activities on the UW campus.