Energy efficient spin-torque devices

在大多数电子设备中，只有电子的电荷被利用，而另一个特征自旋具有未开发的优势。电子的自旋是一种量子力学特性，它为实现未来几代电子产品提供了优势，这些电子产品可以在消耗更少能量的同时运行得更快。迄今为止，自旋电子学的大部分研究都集中在铁磁材料上，其中所有的自旋都在同一方向上排列，并且相对容易读、写和高保真地存储信息。目前，人们认为，在另一类称为铁磁体的材料中，自旋的操纵可能更快，而且可能更节能，在这种材料中，不同原子的自旋指向相反的方向。在这个项目中，pi建议研究基于铁磁的设备，并探索读写信息的新方法。将开发新的器件结构和理论模型。这项研究的结果将潜在地影响存储器、逻辑、数据存储、神经形态计算和射频设备的广泛应用。此外，该项目将为研究生和本科生提供宝贵的培训机会，特别是来自代表性不足和少数群体的学生。此外，私人机构将积极参与地方或国家活动中直接与公众接触的活动。近年来，铁磁体以其独特的性能引起了人们的广泛关注。在完全补偿的铁磁体中，交错力矩导致净磁化为零，这使得自旋电流穿透更深，这是提高自旋-转矩转换效率的潜在非常有用的特征。在铁磁体的角动量补偿点也存在着有趣的物理现象，在那里，有限磁化和非零自旋极化持续存在，使得探索铁磁体中的反铁磁类快速动力学成为可能。在本项目中，pi将对基于铁磁体的器件进行联合实验-理论研究，特别是可以通过电流切换磁化的自旋传递转矩和自旋轨道转矩效应。pi将开发新型器件，其中铁磁体将主动参与磁电阻和自旋角矩传递过程，而不是被动地为系统提供垂直磁各向异性。研究了两端和三端器件，分别了解了自旋传递扭矩和自旋轨道扭矩效应。研究自旋极化隧道电流与铁磁体两个亚晶格的相互作用，了解不同自旋力矩（类阻尼与类场）的作用，并在低至100ps的开关实验中实现可能的反类铁磁动力学。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In most electronic devices, only the charge of electrons is utilized while another feature spin has unexplored advantages. The spin of electrons is a quantum-mechanical property that offer advantages to achieve future generations of electronics that can operate faster while consuming less energy. To date, most activities in spintronics have largely been focused on ferromagnetic materials where all the spins are aligned in the same direction and is relatively easy to read, write and store information with high fidelity. Currently, it is believed that the manipulation of spin can be even faster and potentially more energy efficient in another class of material called ferrimagnets, where the spins of different atoms point in opposite directions. In this project, the PIs proposes to investigate ferrimagnets-based devices and explore new methods to read and write information. Novel device structures, and theoretical models will be developed. The results of this research will potentially impact a wide range of applications in memory, logic, data storage, neuromorphic computing, and radiofrequency devices. In addition, the project will provide valuable training opportunities for graduate and undergraduate students, specifically from underrepresented and minority groups. In addition, the PIs will actively participate in direct outreach to the public in local or national events.In recent years, ferrimagnets have gained a great deal of attention due to their unique properties. The staggered moments in fully compensated ferrimagnets result in a zero net magnetization, which allows spin currents to penetrate much deeper, a potentially very useful feature in increasing the efficiency of spin-torque switching. Intriguing physics also exists at the angular momentum compensation points of ferrimagnets, where a finite magnetization and nonzero spin polarization persist, enabling the exploration of antiferromagnetic-like fast dynamics in ferrimagnets. In this project, the PIs will carry out a joint experimental-theoretical investigation on devices based on ferrimagnets, specifically, on spin-transfer torque and spin-orbit torque effects where the magnetization can be switched by an electric current. The PIs will develop novel devices where the ferrimagnets will be actively participating in the magnetoresistance and spin angular moment transfer process, instead of only passively providing perpendicular magnetic anisotropy to the system. Both two-terminal and three-terminal devices will be investigated, to understand the spin-transfer torque and spin-orbit torque effects, respectively. The research will be focused on the interaction of spin-polarized tunneling current with the two sublattices of ferrimagnets, to understand the roles of different spin torques (damping-like vs field-like) and to realize possible anti ferromagnetic-like dynamics in switching experiments down to 100ps.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.