GOALI: Novel Magnetic Structures for Energy-Efficient Spin-Based Electronic Devices

摘要：自旋电子学通常被称为自旋电子学，它除了利用电子的电荷外，还利用电子的自旋来提供功能更强大、能效更高的设备。近年来，自旋传递扭矩的概念因为在计算机存储器和基于自旋电子学的逻辑器件中提供了高密度而受到广泛的关注。然而，现有的电子自转扭矩效率很低，因此需要高电流在设备中存储信息。阿拉巴马大学和IBM研究中心的大学-工业团队的这项提案提出了一项对基于自旋的新型电子设备结构的研究，这种结构利用一种潜在的极其有效的方法来产生自旋转移扭矩-通过磁性多层结构中的温差产生自旋电流。了解界面上的自旋转移性质，并成功地演示所提出的概念，可以大大提高基于自旋的器件的能效，从而开辟新的应用领域。拟议的项目需要多学科的努力，这将对科学知识、教育宣传和基础设施作出重大贡献。项目人员将在与拟议研究有关的几个正在进行的教育和外联活动中发挥关键作用。这些措施包括与当地学校合作，促进高中生参与研究、公共旅游和演示。拟议的项目将研究一种新的自旋电子器件概念，解决目前自旋转移扭矩器件所需的高写入电流问题。该项目目标背后的物理原理是基于最近的一项理论预测，该预测概述了一条提高自旋扭矩效率的热路线，这是切换超薄磁层所需的。关键材料是一种磁性绝缘体，它在热激励时会产生自旋波(或磁振子)。最终的结果是，当磁子将自旋信息传递给相邻导电间隔层中的传导电子时，自旋极化电流被放大。提出的热磁方法有可能在自旋转移扭矩装置中实现一到两个数量级的量子产额。这项研究合作将从根本上发展新的知识和理解，从理论上预测氧化物基磁绝缘体中产生的磁子产生的热自旋扭矩效应。应对候选异质结中的自旋扭矩和自旋泵浦行为进行基础研究。图案化纳米结构的铁磁共振、磁光技术和磁性显微镜将阐明热自旋转移扭矩效应，并量化热-自旋-电流转换效率。应采用独特的合成策略，利用磁性尖晶石氧化物和石榴石薄膜的低温生长过程，这预计对整合一套不同的材料至关重要。

Abstract:Spin-based electronics, commonly referred to as spintronics, exploits the spin of the electron in addition to its charge to provide more functional and energy-efficient devices. In recent years the concept of spin-transfer torque has gained much attention since it offers high density in computer memory and logic devices based on spintonics. However, existing electronic spin-torque efficiency is low, and, as a result, requires high current for information storage in devices. This proposal from the university-industry team at the University of Alabama and IBM Research Center puts forward an investigation into novel spin-based electronic device structures that utilizes a potentially extremely efficient means of generating spin-transfer torque - by spin currents generated by a temperature difference in magnetic multilayer structures. Understanding the spin transfer properties at the interfaces and successful demonstration of the proposed concept can lead to considerable improvement in the energy efficiency of spin-based devices that will open up new applications. The proposed project requires a multidisciplinary effort that will make significant contributions to scientific knowledge, education outreach and infrastructure. Project personnel will play a key role in several ongoing education and outreach activities related to the proposed research. These include collaboration with local schools to facilitate participation by high school students in research, public tours and demonstrations.The proposed project will investigate a novel spintronic device concept that addresses the issue of high write currents required for present spin-transfer torque devices. The physical principle behind the project goals is based on a recent theoretical prediction that outlines a thermal route of enhancing the spin torque efficiency required to switch an ultra-thin magnetic layer. The key material is a magnetic insulator which generates spin waves (or magnons) when thermally excited. The net result is amplification in the spin-polarized current when the magnons transfer spin information to the conduction electrons in an adjoining conducting spacer layer. The proposed thermagnonic method has the potential for achieving one to two orders-of-magnitude greater quantum yield in spin-transfer torque devices. The research collaboration will develop fundamentally new knowledge and understanding of the theoretically predicted thermal spin-torque effect from magnons generated within oxide-based magnetic insulators. Fundamental investigations of spin-torque and spin-pumping behavior in candidate heterostructures shall be undertaken. Ferromagnetic resonance, magneto-optic techniques, and magnetic microscopy of patterned nanostructures shall elucidate the thermal spin-transfer torque effect and quantify the thermal-to-spin-current conversion efficiency. Unique synthetic strategies shall be pursued that exploit low temperature growth processes for magnetic spinel oxide and garnet films, which is expected to be crucial for integrating a disparate set of materials.