CAREER:Toward ultra-low energy switching in spintronic devices

职业：自旋电子器件中的超低能量开关

• 批准号: 1554011
• 负责人: Weigang Wang
• 金额: $ 50万
• 依托单位: University of Arizona
• 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: 2016-02-01 至 2023-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1554011&HistoricalAwards=false
• 关键词: CAREER; Toward; ultra; low; energy

Spintronics makes explicit use of spin, an inherent quantum-mechanical property of electrons, to achieve novel functionalities. A unique advantage of spintronic devices is their nonvolatility: the information they store in spin is retained and remembered even after power is removed from the devices. Nonvolatility is particularly important for the nascent generation of digital devices in which transistor dimensions will be reduced to only a few nanometers. At this nanoscale the power consumption of traditional complementary metal-oxide semiconductor (CMOS) transistors will be dominated by leakage current; whereas, for spintronic structures such energy waste can be completely eliminated. An important draw back for spintronics is the lowest recorded switching energy to flip electron spins between their up or down states to 1s and 0s in binary computer instructions, is still more than two orders of magnitude higher than a CMOS transistor, which severely limits the present applications of spintronic devices. This CAREER project is focused on exploring novel voltage effects to greatly reduce the switching energy of spin-based devices. By successfully demonstrating ultra-low energy switching, this project broadly impacts a wide range of spintronic devices as well as emergent technologies such as wearable computers and the Internet of Things, for which zero power consumption in the standby state is critical and highly desired. The multidisciplinary nature of the research impacts multiple levels of education, from high school to graduate students. The education activities build on a proven plan to encourage and inspire underrepresented minority students in local high schools to pursue STEM majors in college. Moreover, the PI will leverage this CAREER research to continue his outreach efforts to improve the general public's understanding of spintronics through activities such as 'Physics Open House' and 'Physics Phun Nite'.This CAREER award explores energy-efficient switching mechanisms in spintronic structures. Three different, but complementary approaches will be studied: (1) switching based on voltage-controlled interlayer exchange coupling; (2) switching based on voltage-induced effective field; and (3) switching based on voltage-assisted spin transfer torque. These three switching scenarios are studied under the context of voltage-controlled anisotropy and voltage-controlled magnetism. Voltage-controlled anisotropy is an electronic effect where the magnetic anisotropy field can be substantially modified, but the saturation magnetization remains largely the same. Voltage-controlled magnetism is an ionic effect where both the magnetic anisotropy field and the saturation magnetization can be controlled by voltage. The dependence of these effects on the Rashba spin-orbit coupling and Dzyaloshinskii-Moriya Interaction will investigated. Combined with the experiments that characterize the voltage-induced charge redistribution in ferromagnets, a complete understanding on different switching mechanisms will be achieved. Furthermore, these new approaches to dramatically decrease the switching energy will be directly implemented on high quality magnetic tunnel junctions with strong perpendicular magnetic anisotropy, which can not only perform as stand-alone spintronic memories or logic cells, but can serve also as the essential part of many other spintronic devices, such as lateral spin valves and spin-Hall memories. The results obtained in this project will transform our understanding of how magnetoelectric coupling is mediated by both electrons and ions in ultra-thin magnetic films. Success for this project paves a path to ultra-low switching energy spintronic devices that could be complementary, or even superior, to traditional CMOS devices.

Spintronics明确地使用自旋（电子的固有量子力学特性）来实现新的功能。 Spintronic设备的一个独特优势是它们的不易作用：即使从设备中删除了电源后，它们存储在Spin中的信息也会保留和记住。非挥发性对于新生的数字设备的新生生成尤其重要，其中晶体管尺寸将仅降低至几纳米。在这种纳米级，传统的互补金属氧化物半导体（CMOS）晶体管的功耗将由泄漏电流主导。而对于自旋结构，可以完全消除这种能量浪费。 Spintronics的一个重要吸引力是在二进制计算机说明中向上或向下旋转到1s和0s之间的最低记录的开关能量，仍然比CMOS晶体管高两个以上的数量级，这严重限制了自旋设备的当前应用。该职业项目的重点是探索新型电压效应，以大大减少基于旋转的设备的开关能量。通过成功展示超低的能源转换，该项目广泛影响了广泛的自旋设备以及新兴的技术，例如可穿戴计算机和物联网，对于待机状态下的零功耗至关重要且高度令人期望。研究的多学科性质会影响从高中到研究生的多个教育。教育活动以验证的计划为基础，旨在鼓励和激发当地高中代表性不足的少数族裔学生在大学中攻读STEM专业的学生。此外，PI将利用这项职业研究来继续他的外展工作，以通过“物理开放日”和“ Physics Phun Nite”等活动来提高公众对Spintronics的理解。该职业奖探讨了Spintronic结构中的节能开关机制。将研究三种不同但互补的方法：（1）基于电压控制的层交换耦合的切换； （2）基于电压诱导的有效场切换； （3）基于电压辅助自旋传输扭矩切换。在电压控制的各向异性和电压控制的磁性的背景下，研究了这三个切换方案。电压控制的各向异性是一种电子效应，可以对磁各向异性场进行实质性修改，但是饱和磁化的磁化率基本相同。电压控制的磁力是一种离子效应，其中磁各向异性场和饱和磁化强度都可以通过电压控制。这些影响对Rashba自旋轨道耦合和Dzyaloshinskii-Moriya相互作用的依赖性将研究。结合表征电压诱导的电荷重新分布的实验，将对不同的开关机制有完整的了解。此外，这些新的方法可以显着降低开关能量，将直接在具有强烈垂直磁各向异性的高质量磁性隧道连接处实现，这不仅可以作为独立的Spintronic记忆或逻辑细胞的性能，而且还可以作为许多其他纺纱设备的重要组成部分，例如后期的Spinal Spinal Memories和Spinal旋转式旋转式旋转式旋转式Memories。该项目中获得的结果将改变我们对超薄磁性膜中电子和离子介导的磁电耦合如何介导的理解。该项目的成功铺平了一条通往超低开关的能量自旋设备的途径，该设备可能是互补的，甚至是传统的CMOS设备。