Spin Transport Studies In Band And Interface Tailord Materials: Towards Total Spin Polarization For Spin Electronics

带和界面定制材料中的自旋输运研究：自旋电子学的总自旋极化

• 批准号: 0504158
• 负责人: Jagadeesh Moodera
• 金额: $ 43.75万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-11-01 至 2012-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0504158&HistoricalAwards=false
• 关键词: Spin; Transport; Studies; Band; Interface

Nontechnical:Enabled by advances in basic research as well as driven by a rising demand for ultra-high density magnetic storage, there is an enormous interest of late in devices based on electron spin transport. In this NSF sponsored project we will investigate fundamental properties as well as applied aspects of magnetism related to this, with an expected impact on the field at the basic level as well as the future spin-based information technology. To reach this goal, spin-polarized transport studies of several novel systems will carried out, and to understand and manipulate the spin polarization, P (the degree to which transport electrons are spin polarized), and develop "tailored" materials. For example, we will explore the Cobalt-Iron_Boron alloy system, which recently demonstrated very large tunneling magnetoresistance (TMR) values (the higher it is the more useful for application), to achieve even higher P and TMR values. This material system remains largely unexplored and this study should open the way for candidate materials where P approaches 100%, without the interface problems of a half metal ferromagnet. Ferromagnet-insulator interface bonding is crucial in controlling the magnitude of P. We will aim at controlling this bonding for higher P. The possibility to make structures on a nanometer scale with well-tailored materials and interfaces will allow us to create new materials that show suitable properties. In particular, spin-polarized transport through quantum islands gives rise to novel effects such as spin-resonant tunneling, which can greatly enhance the TMR (observed in our laboratory) with the possibility of making spin transistors. The education of students in science through this outreach program will continue in an effective way to meet the national need for enhanced science education. Continuing the tradition, along with training graduate students and postdoctoral researchers, undergraduates and high-school students extensively participate in this research. It will enormously benefit these younger generation by getting trained for future spin based nano technology.Technical:In this NSF supported individual project a series of investigations are proposed that focus on fundamental properties as well as applied aspects of magnetism, which will benefit both at the basic level as well as for the future spin-based information technology. Spin-polarized transport studies of several novel systems will be done to understand and manipulate the spin polarization (P), necessary for future spin devices. The role of the ferromagnet-insulator interface bonding is crucial in controlling the magnitude of P. Our aim is to control this bonding and explore novel tunnel barriers to achieve higher P, including the exploration of the Co-HfO2 system, predicted to have P=100%. Spin filter tunneling is one of the few ways in which near 100% P (demonstrated in our group in the past), which will be explored for achieving P=100% above LHe temperatures. Based on the electronic structures of the constituent CoB and FeB alloys, we believe it is possible to "tailor" the (Co,Fe)-B band hybridization to achieve even higher P and tunnel magnetoresistance (TMR) values. This material system remains largely unexplored and should open the way for candidate materials with high P, without the interface problems of a half metal ferromagnet. Exploiting dimensionality on a nanoscale, in particular, spin-polarized transport through quantum islands can give rise to novel effects such as spin-resonant tunneling, which can greatly enhance the TMR, as has been observed in our laboratory. Double magnetic tunnel junctions exploiting non-equilibrium spin accumulation and ballistic spin transport will be explored, with potential for novel devices such as spin transistors. As in the past in addition to graduate students, postdoctoral researchers and visiting scientists, undergraduates and high-school students participate in this research program. The education of students in science through this outreach program will continue in an effective way to meet the national need for science education.

非技术性：基础研究的进步以及对超高密度磁性储存的需求不断增长所驱动的，后期在基于电子自旋传输的设备中引起了极大的兴趣。在这个NSF赞助的项目中，我们将研究与此相关的磁性的基本属性以及磁性的应用方面，并预期对基本水平的现场以及未来的基于旋转的信息技术产生了影响。为了实现这一目标，将对多个新型系统进行自旋偏振运输研究，并了解和操纵自旋极化，P（传输电子旋转极化的程度），并开发“量身定制”的材料。 例如，我们将探索钴-Iron_boron合金系统，该系统最近证明了非常大的隧穿磁磁性（TMR）值（对应用程序对应用的有用越高），以实现更高的P和TMR值。该材料系统仍然在很大程度上没有探索，这项研究应为P接近100％的候选材料打开道路，而没有半金属铁磁铁的界面问题。 Ferromagnet-uslator界面键合对于控制P的大小。我们将旨在控制这种粘结以进行更高的P。合适的特性。特别是，通过量子岛的自旋偏振转运产生了新的效果，例如自旋谐振隧道，这可以极大地增强TMR（在我们的实验室观察到），并有可能制造自旋晶体管。通过此外展计划对学生的教育将以有效的方式继续，以满足国家对加强科学教育的需求。延续这一传统，以及培训研究生和博士后研究人员，本科生和高中生都广泛地参与了这项研究。它将通过接受基于旋转的纳米技术的培训来极大地使这些年轻一代受益。技术：在NSF支持的个人项目中，提出了一系列调查，专注于基本属性以及应用磁性的应用方面，这两者都会受益于两者。基本水平以及未来的基于旋转的信息技术。将进行几种新型系统的自旋偏振运输研究，以了解和操纵自旋极化（P），这对于将来的自旋设备所需。铁磁性绝缘体界面键合的作用对于控制P的大小至关重要。我们的目的是控制这种粘结并探索新的隧道屏障以实现较高的P，包括探索Co-HFO2系统，预计具有P = 100％。旋转滤波器隧道是接近100％P（过去在我们的组中证明的几种方式）的方式之一，这将用于探索以高于LHE温度的P = 100％。基于组成棒和2月合金的电子结构，我们认为可以“量身定制”（CO，FE）-b带杂交以实现更高的P和隧道磁磁耐药性（TMR）值。该材料系统在很大程度上尚未探索，并应为具有高P的候选材料打开道路，而没有半金属铁磁铁的界面问题。在纳米级上利用维数，特别是通过量子岛的自旋偏振转运会产生新的效果，例如自旋谐振隧道，就像在我们的实验室中观察到的那样，可以极大地增强TMR。将探索利用非平衡自旋积累和弹道自旋传输的双磁隧道连接，并具有新型设备（例如自旋晶体管）的潜力。就像过去一样，除了研究生，博士后研究人员和访问科学家，本科生和高中生还参加了该研究计划。通过此外展计划对学生的教育教育将以有效的方式继续满足国家对科学教育的需求。