Ferrimagnetic Insulator Enabled Quantum Spintronic Effects and Devices

在这项拟议的研究中，PI建议首先利用脉冲激光沉积合成外延磁性绝缘体或FMI薄膜(例如Y3Fe5O12或YIG)，制备基于FMI的纳米自旋电子器件，并研究这些自旋电子器件的独特物理性质和新功能。FMI薄膜还没有得到很好的研究，也没有被广泛应用于电子器件中，但它已经变得越来越重要，因为它可以使一系列全新的自旋电子器件成为可能。例如，在FMI中，自旋波或磁子可以被激发、传输和利用，从而通过在可能用作非易失性存储器的纳米级器件中的自旋动量转移来有效地驱动域壁。另一个例子是，FMI中的热流携带的自旋电流可以转换为电压信号，这被称为自旋塞贝克效应。此外，通过使FMI接近具有狄拉克能量色散的材料(例如，石墨烯和拓扑绝缘体)，界面上的交换相互作用可以导致量子化反常霍尔效应，这是由器件中的量子化边缘通道产生的效果。这些新奇的现象最近已经被预测或正在进行实验探索。在这项拟议的研究中，PI旨在研究FMI材料和支持FMI的量子自旋电子器件。智力优势：拟议的研究将整合几种独特的材料(如FMI、石墨烯和拓扑绝缘体)，以发现不同的集体现象和功能，尽管包括PI本人在内的研究人员正在积极研究个别材料的许多性质。这项拟议的研究可能会产生非常令人兴奋的新结果，这些结果可以促进我们对材料、它们的界面和相关新物理的基本理解。目前，在这一领域的实验工作还很少。这项拟议的研究代表了旨在推动该领域发展的一项重大新努力。更广泛的影响：这项拟议研究的广泛影响包括以下两个方面。首先，自旋电子学是一个相对年轻和蓬勃发展的领域。自旋电子的一个主要目标是向现有设备引入新的自旋相关功能，例如在我们现代生活中无处不在的基于自旋的非易失性存储设备。这项拟议的研究将探索用于自旋电子非易失性存储器和量子信息处理的新设备概念。这些突破可能会激励工业实验室的研究人员开发更节能、更高性能的非易失性存储设备。PI本人在采用先进设备应用的新概念方面拥有丰富的经验。其次，这项拟议的研究将把本科生和研究生教育与前沿研究活动结合起来。特别是，少年警卫队将积极参与这项研究，这些少数民族学生占比S学校学生总数的很大一部分。在过去四年里，作为本科咨询委员会的主席，PI一直在积极推动PI？S部门将所有物理专业的学生都纳入本科研究的雄心勃勃的目标，PI将继续招募更多的本科生参加这个项目和其他资助的研究项目。PI将把这项拟议研究的成果纳入他最近开发和教授的新的研究生和本科课程。他将继续开展他独立或与物理系联合发起的K-12教育和外展活动。

In this proposed research, the PI proposes to first synthesize epitaxial magnetic insulator or FMI films (e.g. Y3Fe5O12 or YIG) using pulsed laser deposition, fabricate FMI-based nanoscale spintronic devices, and investigate the unique physical properties and novel functionalities of these spintronic devices. FMI thin films have not been well studied or widely used in electronic devices, but have become increasingly important because they could enable a host of brand new spintronic devices. For example, in FMI, spin waves or magnons can be excited, transmitted, and exploited to efficiently drive domain walls via spin momentum transfer in nanoscale devices that can potentially serve as non-volatile memory. Another example is that the spin current carried by a heat current in FMI can be converted into a voltage signal which is known as the spin Seebeck effect. Furthermore, by bringing FMI in proximity to materials that have the Dirac energy dispersion (e.g. graphene and topological insulators), the exchange interaction at the interface can result in the quantized anomalous Hall effect, an effect produced by quantized edge channels in the devices. These novel phenomena have been recently predicted or are currently being explored experimentally. The PI aims to study FMI materials and FMI-enabled quantum spintronic devices in this proposed research. Intellectual merit: The proposed research will integrate several unique materials (e.g. FMI, graphene, and topological insulators) to discover distinct collective phenomena and functionalities, although many properties of individual materials are being vigorously investigated by researchers including the PI himself. This proposed research will likely yield very exciting new results that can advance our fundamental understanding of materials, their interfaces, and related new physics. Currently, the experimental work in this particular area is scarce. This proposed research represents a significantly new effort aiming to advance the field. Broader impacts: The broad impacts of this proposed research contain the following two aspects. First, Spintronics is a relatively young and thriving field. A primary objective of Spintronics is to introduce new spin related functionalities to existing devices, such as spin-based non-volatile memory devices that are ubiquitous in our modern lives. The proposed research will explore new device concepts for spintronic non-volatile memory and quantum information processing. The breakthroughs will likely inspire the researchers in industrial labs to develop more energy efficient and high-performance non-volatile memory devices. The PI himself has extensive experience in adopting new concepts for advanced device applications. Second, this proposed research will integrate the undergraduate and graduate education with the cutting-edge research activities. In particular, the PI will actively engage into this research the under-represented minority students which make up a significant portion of the student population in PI?s institution. Aligned with PI?s departmental ambitious goal in involving all physics majors in undergraduate research, which has been aggressively pushed by the PI in the past four years as the chair of the Undergraduate Advising Committee, the PI will continue to recruit more undergraduates into this and other funded research projects. The PI will incorporate the outcomes of this proposed research into the new graduate and undergraduate courses that he recently developed and taught. He will continue to pursue the education and outreach activities with K-12 that he initiated independently or jointly with the Physics Department.