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Thermal gradient engineering for spin injection and transport in metallic nanomagnetic switches and sensors

金属纳米磁性开关和传感器中自旋注入和传输的热梯度工程

基本信息

批准号：
1610904
负责人：
Barry Zink
金额：
$ 31万
依托单位：
University of Denver
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2016
资助国家：
美国
起止时间：
2016-07-01 至 2019-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1610904&HistoricalAwards=false
关键词：
Thermal gradient engineering spin injection

项目摘要

The electronic and magnetic devices that currently enable rapid information processing and massive data storage are formed in part using metallic structures with dimensions approaching 100 nanometers. Often these devices function due to an applied flow of electrons, and this charge flow generates heat. In many cases this heat limits the performance of these tiny devices and prevents gains in technology. This project aims to explore ways to simultaneously avoid or exploit this heating by study of thermal effects in a particular nanoscale metallic magnetic device known as a non-local spin valve. These devices are already known to allow generation of flows of angular momentum, or spin, in a metallic nanowire with no associated charge flow. However, their operation usually requires large applied electron flows in other elements of the device. The main motivation of this work is to provide the transformative knowledge of thermal effects in these devices that could eventually allow operation with only applied heat, eliminating the charge flow altogether. This will enable simplification and further size reduction in future devices that could significantly advance data storage and other technologies.The metallic non-local spin valve is an invaluable, though still not thoroughly understood, device for producing and studying pure spin currents. The use of charge currents to produce spin currents in the NLSV was achieved ~15 years ago, and these sensors are poised to play an important role in near-term magnetic recording. However, the electrical injection of spin causes significant heating and thermoelectric effects that strongly affect the performance of the sensors are not yet well characterized and understood. The demonstration of spin injection in the non-local spin valve via purely thermal effects is of even greater interest. These very recent and novel measurements point the way toward implementation of such sensors without the large charge current, which offer many advantages for the ever smaller and more sensitive sensors or more efficient sources demanded by the information technology community. This project takes advantage of unique expertise in creating and measuring thermal gradients and in measuring Seebeck and Peltier effects in nanoscale systems to understand and control heat and spin flow in metallic nanomagnetic devices. The unique ability to directly measure the thermal properties (thermal conductivity, Seebeck, and Peltier coefficients) of the thin film constituents of nanoscale devices using micromachined thermal isolation platforms is a central focus of the project. By removing the bulk substrate from beneath a nanoscale device or thin film, the uncertainty in the direction of heat flow is dramatically reduced, modeling the structure via finite element methods becomes much simpler, and engineering the thermal gradients applied to the nanoscale structures is possible. Specific tasks include: 1) Understanding interface and materials dependence of the spin-dependent Seebeck effect and the absolute Seebeck effect, 2) the Search for magnon-drag contributions, 3) Studies of thermoelectric effects and the spin injection in "zero substrate" devices, and 4) Thermally engineering response of sensors via external thermal gradients.

目前能够实现快速信息处理和海量数据存储的电子和磁性设备部分使用尺寸接近100纳米的金属结构形成。通常，这些器件由于所施加的电子流而起作用，并且该电荷流产生热量。在许多情况下，这种热量限制了这些微型设备的性能，并阻止了技术的进步。该项目旨在通过研究称为非局部自旋阀的特定纳米级金属磁性器件中的热效应，探索同时避免或利用这种加热的方法。已知这些器件允许在金属纳米线中产生角动量流或自旋流，而没有相关的电荷流。然而，它们的操作通常需要在器件的其他元件中施加大量电子流。这项工作的主要动机是提供这些设备中热效应的变革性知识，最终可以允许仅应用热量进行操作，完全消除电荷流。这将使未来的设备能够简化和进一步减小尺寸，从而显著推进数据存储和其他技术。金属非局域自旋阀是一种非常宝贵的，尽管还没有完全理解，用于产生和研究纯自旋电流的设备。在NLSV中使用电荷电流产生自旋电流是在大约15年前实现的，这些传感器有望在近期的磁记录中发挥重要作用。然而，自旋的电注入导致显著的加热和热电效应，强烈影响传感器的性能尚未得到很好的表征和理解。通过纯粹的热效应在非局域自旋阀中的自旋注入的演示更令人感兴趣。这些非常新的和新颖的测量指向实现这样的传感器而没有大的充电电流的方式，这为信息技术社区所要求的更小和更灵敏的传感器或更有效的源提供了许多优点。该项目利用在创建和测量热梯度和测量塞贝克和珀尔帖效应在纳米级系统中的独特的专业知识，以了解和控制金属纳米磁性器件中的热和自旋流。该项目的核心是利用微机械隔热平台直接测量纳米级器件薄膜成分的热性能（热导率、Seebeck和Peltier系数）。通过从纳米级器件或薄膜下方移除体衬底，热流方向的不确定性显著降低，经由有限元方法对结构进行建模变得简单得多，并且工程化施加到纳米级结构的热梯度是可能的。具体任务包括：1）理解自旋相关Seebeck效应和绝对Seebeck效应的界面和材料依赖性，2）寻找磁振子阻力贡献，3）研究热电效应和“零衬底”器件中的自旋注入，以及4）通过外部热梯度的传感器的热工程响应。