CAREER: Novel Spintronics Devices based on symmetry-broken systems

职业：基于对称破缺系统的新型自旋电子器件

• 批准号: 2047118
• 负责人: Xin Fan
• 金额: $ 50.08万
• 依托单位: University of Denver
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-02-01 至 2026-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2047118&HistoricalAwards=false
• 关键词: CAREER; Novel; Spintronics; Devices; based

Spin is an intrinsic property of the electron, causing it to behave as a miniature magnet that can be moved in materials by an electric current. The field of spintronics aims to harness the electron spin to connect different physics fields of electricity, magnetism, and optics, etc. One of the first applications of spintronics was in the hard disk drive read head, which significantly increased storage density, accelerating the development of computers and the internet. In recent years, new developments in spintronics have led to a plethora of novel applications, such as magnetic random access memories that are fast and non-volatile, and Terahertz pulse generators that are powerful and economic. These applications are all based on the interactions between electric currents and electron spins. This CAREER project aims to develop and understand new interactions between electric currents and electron spins by using novel materials/structures with broken symmetries. Compared to traditional spintronics devices, the use of symmetry-broken systems will unlock new functionalities. Success in this proposed research will expedite the development of next-generation non-volatile memory and logic devices with enhanced energy efficiency and inspire development of new spintronics devices such as light helicity and surface magnetization detectors. The teaching and outreach activities include by leveraging the proposed research, the PI will design undergraduate and graduate course modules that integrate hands-on experiments in magnetism by using lab tools as well as smartphone applications. The PI will continue to host online spintronics seminars and online tutorials, which will serve as a platform for educating and attracting young scientists. Driven by the spin-orbit interaction, the interconversion between electric current and spin current in conventional nonmagnetic materials generally follows the spin Hall symmetry, such that the electric current, spin current and spin orientation are all orthogonal to each other. This symmetry restriction makes it challenging to generate out-of-plane polarized spin current in thin film devices, which is highly desired in practical magnetic memory applications. This CAREER project explores interconversions between electric current and spin current with new symmetries in symmetry-broken systems. The two main categories of symmetry-broken systems to be explored are (1) magnetically-ordered heterostructures and (2) nonmagnetic films with microstructural asymmetry. The symmetry and efficiency of spin current generation will be detected by measuring spin-orbit torque exerted onto a neighboring magnetic layer via complementary optical and electrical techniques. This measurement will serve as a guideline to select and optimize the most efficient systems to generate out-of-plane polarized spin current. Using the optimized system, current-induced damping modulation and field-free switching of perpendicular magnetization will be experimentally studied. In addition, new phenomena based on the spin-charge conversion with unconventional symmetry will also be experimentally explored in optical spin pumping and spin Hall magnetoresistance.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

自旋是电子的内在特性，导致其作为微型磁铁的表现，可以通过电流将材料移动。 Spintronics的领域旨在利用电子自旋连接不同的电力，磁性和光学等物理领域。SpinTronics的第一个应用之一是在硬盘驱动器读取头中，这大大提高了存储密度，从而加速了计算机和Internet的开发。近年来，Spintronics的新发展导致了许多新颖的应用，例如快速且非易失性的磁随机记忆以及强大而经济的Terahertz Pulse Generator。这些应用都基于电流和电子自旋之间的相互作用。这个职业项目旨在通过使用损坏的对称性的新型材料/结构来发展和理解电流和电子旋转之间的新相互作用。与传统的SpinTronics设备相比，使用对称性破裂系统将解锁新功能。在这项拟议的研究中的成功将加快下一代非易失性记忆和逻辑设备的发展，并增强能源效率，并激发新的Spintronics设备的开发，例如光螺旋性和表面磁化检测器。教学和外展活动包括利用拟议的研究，PI将设计本科和研究生课程模块，这些模块通过使用实验室工具以及智能手机应用程序来整合磁性实验。 PI将继续举办在线Spintronics研讨会和在线教程，该研讨会将作为教育和吸引年轻科学家的平台。在自旋轨道相互作用的驱动下，传统非磁性材料中的电流和自旋电流之间的互换通常遵循自旋大厅的对称性，因此电流，旋转电流和自旋方向彼此正交。这种对称限制使得在薄膜设备中生成平面外偏振电流的挑战，这在实用的磁记忆应用中是高度满足的。这个职业项目探讨了电流和旋转电流之间与对称性破裂系统中的新对称性之间的相互转换。要探索的对称性破裂系统的两个主要类别是（1）具有微结构不对称性的磁有序异质结构和（2）非磁性膜。通过通过互补的光学和电气技术测量施加在相邻磁层上的自旋轨道扭矩，将检测到自旋电流的对称性和效率。该测量将作为选择和优化最有效的系统以生成平面外偏光旋转电流的指南。使用优化的系统，将对垂直磁化的电流诱导调制和无场切换进行实验研究。 此外，还将在光学旋转泵送和旋转霍尔磁场上的实验探索基于旋转的转换的新现象。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的审查审查标准来通过评估来通过评估来获得支持的。