DMREF: Collaborative Research: First-Principles Based Design of Spintronic Materials and Devices

* 技术摘要 * 第一性原理理论（DFT及更高）将用于筛选数千种半金属，并选择一组实验可用的起始材料。我们还将开发基于最先进的非平衡绿色函数的模型，以计算其传输特性。在实验上，我们将合成候选材料，测试它们的电，磁和结构特性，并与理论预测进行比较。 然后将反馈这种表征的结果以改进我们的理论方法。 有前途的材料将用更先进的技术（如自旋极化隧穿和局部电极原子探针断层扫描）进行测试，为更先进的建模提供更详细的信息。最有前途的材料将用于原型TMR和（CIP/CPP）-GMR器件。 一个具体的突破性技术目标是设计、制造和演示一种具有垂直各向异性和低磁阻尼的低磁矩半金属，非常适合STT-RAM。这将通过合理设计、计算验证、自旋输运建模、实验表征和器件制造之间的紧密循环工作流程来完成。UA和UVa的几个跨学科课程将被开发，以快速将我们学到的经验教训融入课堂，并为学生提供尖端的培训。该项目开发的软件将部署在NSF NanoHUB上。*非技术摘要 * 在今天的电子设备中，电子是通过它们的电荷来操纵的。 然而，电子有另一种性质，称为“自旋”。 电子的行为就好像它们绕着一个轴旋转。 根据量子力学，电子的自旋轴只能指向两个方向之一，即“向上”或“向下”。 在大多数材料中，上电子和下电子的数量相等，通常这两种类型对电场的反应方式相同。 然而，在磁性材料中，上自旋和下自旋电子的数量可能不同，并且这两种类型的电子可能以不同的方式响应电场。 这种现象的最极端的例子是“半金属”-这意味着一组电子是金属，另一组是绝缘体。一个具体的技术目标是设计、制造和演示具有精心控制的磁特性的半金属，以满足非易失性磁性存储器（旨在取代传统的RAM）的要求。我们的目标是提供一般的半金属和磁性材料的更好的理解，特别是如何可以将“第一原理”计算与实验上可访问的和技术上相关的材料和器件参数。该项目将有助于通过为本科生和高中生提供研究经验来增加STEM劳动力，并将通过其组成和与HBCU教师的合作来增强其多样性。UA和UVa的几个跨学科课程将被开发，以快速将学到的经验教训融入课堂，并为学生提供尖端的培训。

****Technical Abstract****First-principles theory (DFT and beyond) will be used to screen thousands of half-metals and choose a set of experimentally-accessible starting materials. We will also develop models based on state-of-the-art Non-Equilibrium Green Functions to calculate their transport characteristics. Experimentally, we will synthesize the candidate materials, test their electrical, magnetic, and structural characteristics and compare to theoretical predictions. The results of this characterization will then be fed back to refine our theoretical methods. Promising materials will be tested with more advanced techniques (such as spin-polarized tunneling and local-electrode atom probe tomography), providing more detailed information for more advanced modeling. The most promising materials will be used in prototype TMR and (CIP/CPP)-GMR devices. A specific disruptive technology goal is the design, fabrication and demonstration of a low moment half-metal with perpendicular anisotropy and low magnetic damping ideally suited for STT-RAM. This will be accomplished through the tight circular work flow among rational design, computational verification, spin transport modeling, experimental characterization and device fabrication. Several interdisciplinary courses at UA and UVa will be developed to quickly incorporate lessons we have learned into the classroom and provide students with cutting-edge training. Software developed in the project will be deployed on the NSF NanoHUB.****Non-Technical Abstract****In today's electronic devices electrons are manipulated through their electrical charge. However, electrons have another property called "spin". Electrons behave as if they were spinning about an axis. According to quantum mechanics the spin axis of an electron can point in only one of two directions, i.e. either "up" or "down". In most materials there are equal numbers of up and down electrons and usually both types respond to an electric field in the same way. In magnetic materials, however, the number of up and down spin electrons may be different and the two types of electrons may respond to electric fields in different ways. The most extreme example of this phenomenon is a "half-metal" - meaning that one set of electrons is a metal and the other set is an insulator. A specific technology goal is the design, fabrication and demonstration of a half-metal with carefully controlled magnetic properties tailored to meet the requirements of non-volatile magnetic memories (which aim to replace traditional RAM). We aim to provide an improved understanding of half-metals and magnetic materials in general, in particular how one can relate 'first-principles' calculations to experimentally accessible and technologically relevant materials and device parameters. This project will help to increase the STEM workforce by providing research experiences for undergraduates and high school students and will enhance its diversity through its composition and collaboration with HBCU faculty. Several interdisciplinary courses at UA and UVa will be developed to quickly incorporate lessons learned into the classroom and provide students with cutting-edge training.